Ok. You open up UED (unrealed.exe in your UT200*/System folder) and in the texture browser (the window that should be open already) use the File -> Import dialog to import your texture.
You need to give it a unique package name, such as TheRabbitEatsMyDooDoo. Group name isnt essential, but you might as well give it one to make yourself feel cool. Then of course, the texture name itself.
After you've got your texture showing in the texture browser, theres a step or two you'll need to take:
Right click on your texture and select Properties. Then open the [+Texture] submenu to make it turn into [-Texture]
You're going to want to change the LODSet property to LODSET_Interface (that will prevent your team symbol from getting all muddy at low detail settings) and change both the UClampMode and VClampMode properties to TC_Clamp (which will prevent it from tiling on surfaces its applied to)
After thats done, go ahead and save your new texture package and close UED. If it says that other packages have been changed, just click no every time. It lies.
Now you're gonna need to make an extra file so UT knows how to find your team symbol. fire up Notepad or something and throw this in
Code:
[Public]
Object=(Class=Texture,Name=YOURPACKAGE.GROUPNAME.TEXTURENAME,Description="")
(obviously replacing YOURPACKAGE, GROUPNAME, and TEXTURENAME with the ones you had used when you imported the texture)
Save it into your UT200*/System folder as a .int (turns out the TeamSymbol stuff only shows up in the cache manager cause its wrapped to a .int search :X)
So now you should end up with all of two files:
YourTeamSymbol.int in UT200*/System
YourTeamSymbol.utx in UT200*/Textures
You should be able to use the team symbol now all you want.