Greetings! Welcome to Tezzaworld website, unfortunately you are a few years late to the show as nearly everyone has been and gone, there is still lots of useful archived material to read through, not many active users unfortunately, but that’s the way it goes, hopefully you are not too disappointed...
basically take the rail off the standard seat and bolt it back into place. put the bucket seat on top of it and make where the holes need to go. you might have to weld in extra supports as the bucket mightn,t be the same width as the standard seat
Get some cheap steel sidemounts and cut them up so you can position the seat properly then either use the existing bolts or weld them to the runner. I will get some pictures of mine on a powered rail later.
use a hammer to knock a bulge out in roof I've had it before and very annoying you might want to get the rails for them though as they sit a lot lower than the standard Altezza rails, or universal ones wouldn't be too hard to fit