They mostly use a magnet on the spokes and a sensor on the fork so I don't see any easy way to fit one in a working configuration. Maybe with glue and a hacksaw, though.
I use a Garmin eTrek which has good trip computer functions and is quite cheap.
I actually use a computer and the Garmin on my Kalkhoff. The two agree on distance quite closely but it's interesting to see how the GPS varies from the trip computer on a gradient.