Haven't looked into it yet.Its not that hard....once you find the correct pickguard as not all SG pickguards are equal. There's so many slight variations to the SG shape, neck and pickup positions that it can be hard to find one that lines up correctly (even before the routing begins). You really have to do your homework before you purchase one. Even then, you'll may have to drill some extra holes.
Where were you planning to buy the pickguard from?
The other option (which might be less hassle than finding the correct one since you probably have a router) is to make your own. That way you can use your old guard as a template and just add in the P90s instead of humbuckers. You'll just need a template router bit (top bearing) and a chamfer bit for the outside bevel.Note that you might be able to find a ready-made pickguard that matches your screw pattern, batwing outline, and the make/model of P90s you choose
Maybe yes, really not sure.Dr. Are you thinking about converting your Walnut Tribute?
Monetary not a option.Personally, I'd just buy another guitar!
Jason Lollar did a 7 part series on this exact conversion on youtube. Looks like a lot of steps but if you have the tools and skills, it shouldn't be too hard.