Having had issues installing my Rear main seal and destroying one in the process I decided to spend the money and buy the proper tool (Porsche special tool p234). I am very happy with the results and using it was extremely easy. I also had to order 3 extra flywheel bolts to attach the tool to the crank. The reason for this is that the long bolts used for the Dual mass flywheel does not work and you need the short bolts used on the single mass flywheel for the 911/944 (Part number 93010220600).
The tool can be bought from the following sites:
http://shoptoolsshoptools.com/shopexd.asp?id=1138
http://www.samstagsales.com/Porsche.htm
I bought mine from Pelican parts:
http://www.pelicanparts.com/cgi-bin/smart/...Flywheel%20Side
I am also adding some photos showing the installation of the oil seal using this tool
