I'd really like to see a picture of that swing wing F-16!!!

Although I have never built a swing wing model I have discussed the F-14 with Mark Hambleton of DCU models. He said that they originally weighted the wingtips of thier F-14 in order to maintain the CG in relation to the center of lift as the wing sweeps. He also told me that one of his customers' models had recieved some wingtip damage on landing and had been repaired at the field (minus the wingtip weights) and had still flown just fine at all sweep angles, and after doing some tests of his own Mark decided to leave the weights out of future kits.
Mark designed that model, so I would guess that he knows what he is talking about.
As far as working out the CG, I would suggest that you first find the CG for the foward sweep position and the rear sweep position, then for several other postions in between those in 10-15 degree incriments.
I think The USJRC site has a pretty good article for how to figure CG on a highly swept wing planform.
One other interesting thing that Mark told me about swept wings is that it actually is more difficult to move the wings rearward than it is to swing them forward :spinnyeye , if the sweeping mechanism were to break somehow the wing(s) would actually move forward while in flight not backwards as you would expect.

Kevin Whitlow