The UEI setup code is Video 1516, and as you say, the 15-100 doesn't have this code. The hifi-remote.com site has about a dozen Sony BluRay upgrades (all very similar) in the File Section, but the 15-100 doesn't have a JP1 connector--just some holes in the PCB.
I recommend buying a RCA RCRP05B (<$20) or even better an OneForAll  OARUSB04G. This latter remote is programmable directly using a standard USB micro cable.  The JP1 software (RMIR) supports this remote, not that you're likely to need to customize it.