if liquid CO2 gets into the solinoid(sp?), which is very likely, it will **** it up basically, also co2 is a lot harder on internal seals and orings so they will have to be changed more often, just get an air tank
if you really feel it necessary to use it which i would say do not . you need a co2 bottle with an anti siphon tube fitted to ensure co2 does not completely ruin the internals. once that is done you get about 5 shots out then have to wait for the pressure to rise in the gun and fire another few shots. basically wait until you can fill the air bottle.
If you want to know what Co2 does to your Ion. Take the grips off, get a Co2 fire extuingisher and fire it at the circuit board until it runs out. Then try and use it.