Modifying a Point and Shoot

I just loaded the CHDK firmware for my Canon PowerShot A550, so I can do up to a 34min exposure. Now, I was wondering if its possible to remove the lens unit without killing the camera. I would like to use it with prime focus. I know you can take the lens out but I don't know if the camera will still take pictures without it.

Thanks for any help

No. Well, not in the simplest answer to your question. When the camera starts up it moves the lens off the home position and checks that it can detect that it's moved. If the lens isn't there, it gets upset and shuts down. If you're a deft hand with a soldering iron, you can add switches or circuitry to fool it past that point.
I wish CHDK was available for DSLRs.

doesn'nt bulb mode on Canon Dslrs allow for long exopsures

Yes, it does. The CHDK firmware for Canon point-and-shoots adds lots of other functionality not found on DSLRs, as well as longer exposures.

I'm sure it is possible to rewrite the firmware, I used to reprogram my Sony Ericsson k800i this way...