After some edits, this is what I came up with so far. Tested for windows only.
CHDK: preparing your SD cardIf java is not installed and you have no possibility to install it, this method is not for you, go to http://chdk.wikia.com/wiki/Prepare_your_SD_card for alternate options
The best booting method depends on your specific demands and capabilitys.
The firmware update method means that you will have to follow a camera specific set of button presses to load the software each time you start the camera.
The card lock method allows you to start the camera automatically in CHDK with the on/off switch and, if set, can automatically start or restart a script you are running.
CARD LOCK METHODFor camera's produced after 2011 only 1 partition in FAT32 is needed.
Go to Step 1: getting the correct build.
If you are not sure, read on.
Older camera's can only boot from FAT16 partitions.
FAT16 is limited to 4GB max.
If you want to use a pre 2011 camera these are your options to use CHDK:
1) You use the firmware update method and use cards of any size supported by your camera, formatted in FAT, FAT32 or exFAT.
2) You use card locked 4GB or smaller cards, during a shoot you exchange them if one is not enough.
3) You use a card locked SD card with 2 partitions, one FAT16 to boot from and one FAT32 for scripts and pictures.
Trouble creating a dual partition card on Windows?
Use Stick to download the correct package for your cam: Step 1
Format the card in exFAT (default)
Unpack the full version of your build to the card
Insert the card in your cam and use the Firmware update method
Use the <ALT> key to activate CHDK and then [MENU]
Select miscellanious, SD card, make dual partitions
Place the card back in your windows machine and only format the small partition to CANON_DC with FAT
Copy all files except the CHDK folder to the CANON_DC partition
Use Stick to complete installing CHDK on the 2nd partition
Optionally you can copy the files that were not included on the second partition there. This is only usefull if your card might get stuck on the second partition.
Step 1: getting the correct build:1) download stick
http://www.zenoshrdlu.com/stick/stick.html2) and if not installed yet, download java
http://www.java.com/en/download/manual.jsp3) install java, unpack stick
4) get a picture from the camera you want to enhance with CHDK
5) for Windows: start stickx.cmd from the unpacked folder, For Linux open.... and for macOS use .......
6) browse for the picture and let it download the appropriate package after it identifies your camera.
if you have done this before you do not have to download again, but click 'USE IT'.
when stick can't identify your model see the last chapter of this instruction:
'Trouble with getting stick to work?' Step 2: Configuring any SD card to load CHDK via the firmware update method1) unpack the downloaded build from the stick folder to your SD card.
2) insert the SD card in your camera and use the firmware update method described for your model.
For most models this means starting up in PLAY mode, accessing the MENU and use firmware update at the bottom of the settings page.
After that press the SHUTTER button to start the camera with CHDK loaded.
Some models only have the firmware update method available in the MENU by starting the camera normally instead of via the PLAY button.
Configuring any SD card to load CHDK via the card lock boot method1) use 'continue to install step' in stick.
2) if under install tasks it states that the card must be partitioned to autoboot you have an older model camera and a larger than 4Gb SD card.
if you do not want to work with dual partitions, close stick and configure your card for the firmware update method. Or insert a <4GB card and try again.
Be aware
Windows before version 10, Mac and Android can't read dual partitions natively and you need third party software or CHDK running on the camera to swap partitions in order to acces your pictures or add scripts.
3) press 'Install CHDK' and remove and insert the SD card as many times as it asks.
4) lock the card and insert it in your camera, if all has gone well CHDK will autoboot when the camera is started.
Step 3: What now?if you have little experience with CHDK or haven't looked up your specific model to see how to start script or functions in CHDK, go to <link-page:First steps in CHDK>
Making a dual partition card suitable for reuse as a single partition cardif locked, unlock the card and put the card in the camera
format the card
Trouble with getting stick to work?Can't analyse picture or find autobuild: check your firewall settings and internet connection
Still can't find your camera? Check
http://chdk.wikia.com/wiki/For_Developersif your camera is ported.
Stuck in this instruction: write what happened
https://chdk.setepontos.com/index.php?action=post;msg=139420;topic=13689.10Use Chimp or vers.req methode to identify the correct build and download the appropriate build.
Can't acces SD card volume: haven't figured that one out myself
Use Chimp instead
Links to other methods and instructions:http://chdk.wikia.com/wiki/Prepare_your_SD_cardhttp://chdk.wikia.com/wiki/CHDK_Dummies_Guide_2nd_Editionhttp://chdk.wikia.com/wiki/CHDK/Installing_with_Cardtricksseperate page:
First steps in CHDKpress the defined <ALT> key for your camera to enter CHDK mode. The <ALT> key is usually either the PLAY or MODE button. however, some cameras use the PRINT, ALT, DISP, VIDEO, HELP or FACE button so you might have to try different buttons to find the right one.
when in <ALT> mode you see in the bottom left corner 'no script' or whatever script is automatically loaded.
if you are unsuccesfull look up the method for your canon model here.
http://chdk.wikia.com/wiki/For_Developers press the MENU button in <ALT> mode to access the CHDK configuration menus.
press the FUNC/SET button to bring up the scripting menu.
press the shutter button in <ALT> mode to run the currently loaded script.
exit <ALT> by pressing the <ALT> button again. Override settings and onscreen display option will stay enabled while you are back in normal Canon mode.
if the card is <4GB or you have a modern camera you can change the firmware update method to the card lock boot method by navigating to: <ALT>menu>miscellaneous>sdcard>make card bootable.
please be sure to set the card to the locked position before you start the camera.