There are currently only eight Canon camera models with ports of CHDK that have extra code to override the video time limit. These include the ixus230, ixus240, a1200, sx220, sx230, sx240, sx250, and the sx50. Unfortunately, none of these are your camera.
Unless somebody volunteers to dig into the code for your cameras and make the necessary changes (and find someone to test them) then the script you found is pretty much as good as it gets.