As far as I know, the valve cover doesn't have any gaskets. It uses a Loctite #5900 type sealant.
Removing the cover is not easy, as it forms part of the camshaft bearing assembly - the upper bearing face is part of the cover itself.
Engine removal is probably the way to go as it is easier than trying to remove the cover in situ, but somebody with greater experience than me (JFPinPA, ByProdriver, Feelyx et al) can chime in......
2001 Boxster S (triple black). Sleeping easier with LN Engineering/Flat 6 IMS upgrade, low temp thermostat & underspeed pulley.
2001 MV Agusta F4.