CHDK is compatible with a lot of IS and non-IS cameras. IS just means Image Stabilization, and is not an indicator of CHDK support. Check the wiki for the compatibility chart.
The Canon SD1100 is the same as the Ixus 80, both have Image Stabilization, whether it's specifically mentioned or not. Some people, like me, may write it as SD1100 as shortcut, but it still has IS, and there is no non-IS version.
However, the Ixus80IS aka the SD1100IS does not support CHDK as of now. Besides, it only has 3.0x zoom.