Can anyone say that the have complete control of their equipment using a USB-UIRT? It won't even learn codes (well, it learns them, but they do not work when tested.).
I have complete control of my equipment with a USB-UIRT, I am running 0810 Alpha 2.37. The pronto code format is described in great detail in this article: http://www.remotecentral.com/features/irdisp2.htm.
I use IR emitters connected to my USB-UIRT so the IR codes are sent directly to my devices (within inches). I have read that the USB-UIRT can have problems sending IR codes to devices without the emitters. This is likely due to a couple of different issues: attenuation of the IR signals and reflections or scattering of the IR signals, all will interfere with transmission. Have you tried pointing the USB-UIRT at the television's receiver from a few inches away? Another thing to verify: ensure that the timing information is correct in the codes you are using, the pronto article describes how to verify this. You may also try some other Sony TV codes from remotecentral.com's IR Hex code database.
You may also want to check the Com port settings in LMCE for the USB-UIRT, some people have had it change ports on them and stop working, check out: http://forum.linuxmce.org/index.php?topic=8900.0