have a search n the interiors section mate becasue i asked rubjohny the saem question a month ago.
the main jist was it invloes welding work or a recaro subframe (mega bucks), if you weld it get scricco or corrado subframes or mk3 polo adjustable subframes, to act as the base as they're lower and mean if you weld the base up you wont end up sitting on a tower.
its a custom job basically. is it for a 5 door though, as i couldn't find any that would tilt forward for rear passengers?