I think manufacturers sometimes provide prontoscript files. They can also be user created.
I think only the TSU9400, TSU9600, and the soon to be releasedTSU9800 support this with the RFX9400 and RFX9600 receivers (with 4 232 ports, IR ports, and power sesing ports).
Check out the new pronto pros. They are wifi and can do some really cool things over ip and 232. I think they fill the place in the market between crestron/amx and programable remotes.