Charlie,
There isn't a "discretes 101" and getting them into your remote may not be trivial. I don't know much about the AV3000 but I am not sure that any program exists to program discretes directly into that remote. I don’t believe that it has Sony’s widely available discrete commands in its built in library.
The only two remotes that can be programmed *directly* with discretes with freeware/shareware are the Pronto (and it's close variants) and the One-For-All (OFA) remotes. There are also tools to convert the many Pronto files here into commands that can be entered into the OFA remotes. Most of the other remotes must learn a discrete command that as you probably understand is a bit of a conundrum.
Suitable OFA remotes cost ~$25 and maybe (if you can’t solder) another $20 for the PC to JP1 remote interface cable (JP1 is a little 6-pin connector in the battery compartment of certain OFA remotes). Many people buy these to program their other, more expensive, remotes. There is an active support group and to get started go to Rob Crowe's unofficial OFA remote website
www.hifi-remote.com and follow the links to the JP1 Yahoo group.
There is also an active OFA remote discussion group here at RC that is quite active.
-Jon