bike comp?

I have a trice ice nt and Ive just gotten a new bike comp...since I am now using it indoors on a trainer, the old way of mounting the bike comp (on the front wheel) no longer really works (except for the clock)...so Id like to mount it on the back wheel...but Im a little unsure how...there doesnt seem to be a regular distance to mount to...so, Im guessing somthing will have to be fabricated...I was curious if there was anyone else who had this experiance and how they soved it...Id love to see a picture if you have one...