Only for the adventurous: if you would like to try to enable scrollwheel in ML menu in LiveView, you can try this:
#define GUIMODE_ML_MENU guimode_ml_menu // in consts.h
// in menu.c: uncomment code fragments which refer to dbg_menu
// in menu.c, after SetGUIRequestMode(GUIMODE_ML_MENU), add msleep(2000) or so
// recompile with make clean && make
What this does: it allows you to change the GUIMode (as named by Canon engineers). With different modes, camera receives different key events. Some of them will allow wheel events and LiveView at the same time.
The process takes a lot of time (there are maybe around 100 gui modes), you will get a lot of ERR70, black screens or restarts (maybe even worse, hopefully not) and also fake error messages (you get only the dialog boxes, not the actual error).
So far, GUI mode 1 is play mode, 2 is Canon menu, 0 is idle mode. Others are photo mode dialogs (which will cause problems if you try to enable them in LiveView) and others are LiveView dialogs (we are looking for one of those).
Other things to look for:
// choose a gui mode which lets you:
// * use the wheel and all other keys for menu navigation
// * optional: send PRESS SET and UNPRESS SET events (if it doesn't, add an exception under EVENT_1)
// * see LiveView image under menu
// * go back safely to mode 0 (idle) without side effects (check display, Q menu, keys etc)
// * does not interfere with recording
After you change a GUI mode value from the menu, it will take effect when you open the menu next time.
If you get stuck with a gui mode which doesn't let you open the menu, go to Play mode and open ML menu from there. In Play mode, ML doesn't change gui mode, since it already receives wheel events there.
If you get black screen instead of LiveView image, you can usually restore it by pressing PLAY and then shutter half-way.
After you find this constant, look at 550D's consts.h and redefine GUIMODE_ML_MENU in a similar way, with your value (which may be different, e.g. one value good for LiveView, another for "simple" photo mode etc).
P.S. One of the GUI modes in 550D displayed this logo (animated).
