I wouldn't expect help from someone (Terry) who made four posts a year ago, and nothing since.

I have no clue what a GTP-500 or GFA-545 is, but if you find any similar device in the JP1 file collection
[Link: hifi-remote.com]
or the RemoteCentral CCF collection
[Link: remotecentral.com]
we can help you figure out how to program a JP-1 remote for it.

Further JP-1 questions should be asked in one of the forums at
[Link: hifi-remote.com]