Commander off/tv (or whatever device you want)
If the button you want hasn't learned a command, it will flash
press the button-it will stay on
press button on original remote until 3000 beeps
Finished

If the button has learned a command:
Commander off/tv
Press and hold DEL/press the button once and it will flash
press button on original remote until 3000 beeps
Finished

Although you have had your 3000 long enough and are not a newcomer, I will put this in anyway:

These threads will answer your questions, and others which may arise.

RM-AV3000/3100 NEWCOMER’S PACKAGE-WELCOME-CHECK THESE OUT (IF YOU HAVEN’T ALREADY DONE SO) AND SAVE YOURSELF SOME PROBLEMS

AVOID SYSTEM CONTROL PROBLEMS

HOW TO LABEL, CHANGE OR HIDE BUTTONS

CHANGING BATTERIES (May not apply to RM-AV3100-time will tell)

AND IF YOU HAVE A SONY RECEIVER:
CHANGING YOUR RECEIVER AND REMOTE TO AV1 (or AV2) COMMAND MODE