I've read lots and lots of threads and topics about these subjects and I finally decided to change my valve stem seals and to install the RSR seals.
Here is how I've done it, if it can help someone else...
First the valve stem seal:
After removal:
Installation of the new valve stem seals is abundantly covered elsewhere on this forum. I found it difficult to do. You have to be really careful not to get them too far on the guide. I took a lot of measurements but still am not sure of if they are installed correctly. I tried to get them 6mm on the guides as this is what I measured inside the seals.
Then the RSR seals:
Before installation of the RSR seals:
During installation. First you should thouroughly clean the grooves of the shaft. I lubed the seals with engine oil, pulled them over the groove and then pulled them back in the groove. When doing this, you will notice that one side of the seal will be "higher" than the other. The lowest side should face the groove. If this is ok, it will get in the groove easily when you pull them back. If you look closely, you can see what I mean by higher and lower side:
The shaft before driving it in. I've lubed it as recommend by Wayne with assembly lube. Always put the side with the bolt head on the thin side of the camshaft housing.
The shaft after installation. I simply put them flush with the thin side of the camshaft housing:
I lubed the thread of the bolt in order to get a correct torque reading:
Then I tighten the bolt to the correct torque which is between 18 and 20 NM. I've read in lots of threads that people advice 18 Ft/lbs. This is a mistake. Porsche recommends 18 NM. I use a simple 1/4 torque wrench with a hex head that I shortened a little. It works perfectly. Mine is a Hazet that my brother lent me but you can easily find them on ebay or elsewhere.
Another picture of the torque wrench:
I also lubed the the inside of the camshaft housing (where the shafts go), the inside of the rocker arms and the bush and nut of the rocker arm guide as well as the cam itself. I paid special attention as not to rotate the 8mm hex nut.
I know some people recommend to install everything dry but I prefer to follow Wayne's advice. This is especially true for the RSR seals which can easily be cut by the camshaft housing when pushing the shaft inside.