WOW - opened a 7 year old thread for this
anyhow YEA you can do it alone, but after my 4th attempt I got my sone to hold the shifter and I nailed it...dont be afraid to try try again!
I just gave a friend one of my rebuilt stock couplers tonight and will be rebuilding his to a "zero play" unit soon...Installed one in a 964 last night ... these things are pretty easy once you get the feel for it - best of luck!