I don't know how the OmniRemote RF codes are formatted. I can tell you how all X-10 RF codes are formatted. If you will give me an e-mail address, I can send you VB code that will send all of the RF codes from a parallel port using an RF transmitter such as the Ming TX-66 or the RF transmitter board from any of the X-10 universal remotes. You will need a method for generating delays with microsecond resolution, though. But it will show you how the codes are sent. It's very, very simple.
The RF protocol is the same as the original NEC IR protocol except it uses an RF carrier (310MHz in North America - 418MHz and 433MHz in Europe). You can find a description of the NEC protocol at... [Link: vishay.com]
The two data bytes are the same as the 3rd and 4th bytes detailed in the Firecracker protocol on X-10's web site at... [Link: x10.com]
I capture and decode them with a Ming RE-66 RF receiver and a BasicX-24.
There's also a DIY project by Stewart Baker who built his own Palmpad like device using a PIC to generate the IR codes and an RF transmitter to send them. It also shows how to generate the codes. Here's a URL... [Link: geocities.com]