It is possible to make SP maps appear in the main menu. I have most of the Sp in my main menu, and none had to be decompiled. All you need is an .arena file. If you want, I can post the one which I have which came with lugormod.
I would listen to anything by Two Steps From Hell... http://www.youtube.com/watch?v=XYKUeZQbMF0 http://www.youtube.com/watch?v=dJ-QLl5qjLg http://www.youtube.com/watch?v=ASj81daun5Q http://www.youtube.com/watch?v=N2RK6OGNMCY
Ah, I see, well I have some jk2 which have that problem, so this would be good if you imported the textures as well, but you could probably just copy over the whole textures folder..