1: use one of the intervalometer scripts
2: Buy faster hardware. A fast, freshly formatted SD card may help a little, but otherwise canon's continuous shooting rate is almost certainly all the camera is capable of. You may be able to adjust canon settings to get faster capture (try playing with quality and image size) but CHDK can't help you with this. Note that lower resolution is frequently slower, or at least not much faster than the cameras native resolution. Forum search may find you some threads on this, I know it has been discussed before. On some cameras the high ISO mode is significantly faster.
