So I was wondering, is there a script that could take three pictures with one press of the shutter button, at different Tv? I know you can take a JPEG, and RAW with one press of the shutter button, so I think that different Tv would be possible.
This is a "basic" CHDK feature, available in CHDK for a long time:
Tv bracketingEnter <Alt> mode with PRINT, enter CHDK menu with MENU, set up wat you want...

-> set "TV bracketing value" to [2 Ev], "Brackting type" to [+/-], exit Alt mode, use the custom timer (set up to 1s delay, 3 shots)
See also
this post...