I think that you'd best call the BATF, but I actually think that it would be legal, since no transfer of ownership is occuring. It's just like you can ship a gun to a gunsmith, and then he can ship it directly back to you without using an intermediate FFL dealer, again because there is no actual change of ownership. If you do, though, I'd address it only to yourself, and specify that only the addressee (you) may sign for the package.

But, to be safe, I'd contact the BATFe and find out from the guys who would bust you if I'm wrong !

Mike