Don't see why not as long as it's supported properly but Asbestos I assume you mean Asbestos slates if we are talking main roof? Eyeshields,Mask,Disposable overall comes to mind with asbestos even if not dangerous blue asbestos. I doubt you would get a roofer to make good without a considerably high charge dealing with asbestos. If you are putting in the window you are capable of making good just cut the slates to fit around the gap made as per window installation instructions.
Bob
May 2009