oil seals

could anybody tell me if it's possible to fit new valve stem oil seals whilst the head is in place on the 2.5 8v, with the cam removed and lifters out of the way. as you can on some of the ford engines (cvh). by putting number one piston to tdc then droping the valve onto the piston. Can this be done on 944, as it would be a lot less hassle. thanks

This doesn't help but couldn't you hold the valves in place w/ compressed air through the spark plug hole?

Yes you can do it. But use compressed air as 83-944 stated and have the cylinder on TDC as a safety. This is a common practice

would i not loose it through the rings? would air be enough?

You'll lose some air but if you leave the air line hooked up, it'll hold pressure.

So is there a tool for the springs whilst the head is in place?

a valve spring compressor should do.

any of the bottom 4 of these should do. i'd recommend the KD 3271 or 2078. You'll also find the air hold fittings there as well.
http://www.mytoolstore.com/kd/kdengi13.html