I apologize if I sound like an insanely arrogant jerk when you read this, just letting you know the amount of work that goes into this process.
As Master Caine said, you have to take the saber apart in order to change the LED. As I found out with those, it's not just a simple matter of pulling out the blade and putting in an LED. You have to take out the blade, remove the LED string from the blade if you intend to reuse it, crack open the saber, remove most of the electronics from the hilt, rewire and solder the battery pack, sound board, speaker and switch to connect to the LED, drill and tap holes so you can secure the blade or blade holder, get the LED unit attached into the saber and then if you didn't screw anything up, you have a converted saber. It's a lot more work than folks realize, especially if you want it to work when you are done.
I don't think he's talking about getting a Force FX conversion. He said he had an UltraFX, meaning he has a pre-converted one. He just wants to change the one LED to another. Of course, this may involve taking apart the saber, I don't know, I just wanted to clarify that.
Ask Deep, like Master Artorius said. You could also PM Ultra, making sure to post on his thread warning him of the PM, and see if that's a possible custom job (seems like it should be relatively simple).