I got these instructions very easily from RCA's website.
RCU500 - SystemLink 5AV Code Search Instructions
The remote may already be set up to operate your brand of TV, VCR, Laserdisc, Satellite Receiver, Audio Equipment, or Cable Box. It is pre-programmed with the following codes: TV-000, VCR1-000, AUDIO-003, SATCable Box-000, and Laser Disc Player-037. For brands that require programming, there are two ways to program: Using Code Lists or Code Search. Use Code Search if the code lists are not available or if the codes from the lists do not operate a device.
Programming a Device using CODE SEARCH
1. Manually turn on your device (TV, VCR, Laserdisc Player, Satellite Receiver, Cable Box or Audio Equipment).
2. Press and hold CODESRCH.
3. Press and release the device button you want to set up (TV, VCR1, VCR2LD, DSSCABLE, or AUDIO).
4. Release CODESRCH.
5. Press POWER repeatedly until the device turns off (You may have to press up to 100 times).
6. Once the device turns off, press and release ENTER.
7. With the device on, press another button, for example CHANNEL UP. If the device responds, no further programming is required. If the device does not respond, repeat steps 1-7.