You can always use another guitar :)
I'm not sure Vai played on that song, but he may have been in the live band. Could have been John Sykes did the solo, but I know nothing about what else he's done. Vai is from another planet anyway.
Rock on!
!PIZZA !LUV
Vai played on Slip of the Tongue which was the only album of whitesnake I really got into. I only know a few of their hits apart from that. I was looking for a song to do and went hunting for a backing track off of that album, but couldn't find any.
Moving on from rocking - Thinking about funking :)
(BTW - Really enjoyed the interview podcast you did the other day)