I did this to my Squier P.
I used a pencil to dot the corners of the inlay after laying it in place & eyeballing it with the back of the decal still on. Not perfect, but you can't tell anything if off unless you're trying hard to find it. My band mates thought it was a different bass. It's since been converted to a 5.
Painters or masking tape is a good idea too.
