This is actually a two part answer.
First, you need the computer to setup and edit your button layout (if it's not already there). This should be done on a PC, in order to make your life easier.
Second, you can learn commands without a PC, just as Ziggi said. Press and hold Main and Ent at the same time for about 10 seconds until you get to the setup screen. Follow the prompts to learn your buttons from there.
By the way, you will want to get a Belkin or Keyspan serial to USB adapter, since those are the ones URC has tested to work properly. I know for a fact that others, such as Radio Shack, have not worked. I use Belkin and it has been great!
Thank you,
Damon DG
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