Just like hornsfan said, lubricate the splines. Other than that, go ahead and install it into the hub (as long as you have the ball joint bolt out and the spindle free of the lower control arm) to support it on that end while you hammer it in. You can use the weight of the spindle to help force it in also. Installation isn't normally an issue, though. It's more often removal that's a pain in the ass.
Speaking of... I did the clutch yesterday. Drove it to work this morning. Can't wait for my FTC to get here so I can run above OE boost. It took me about 5-6 hours of actual work to finish the job from start to finish. Doing a transmission job in your driveway with the most basic tools, a 3/8" electric impact, a 1/2" impact, is much more time consuming than doing it in a shop. And muscles are sore that normally wouldn't be sore. I have got to get a 3/8" electric ratchet. Milwaukee M12, here I come!
Since the MSP is up and running (for how long, who knows) I'm going to now R&R the RX8 transmission. The input shaft bearing is GONE as well as 2nd, 3rd and 4th gear synchronizers. 2nd went first, and it's been a downhill slope ever since. Remember, kids, if anyone ever gives you a 5 gallon bucket of "Pennzoil 75w90 Synthetic" gear oil, suspect that it's actually something completely different... I could tell in both the cars that the transmissions felt "notchy" and the Speed started getting a hint of grinding going into 3rd... The 8 didn't exhibit any symptoms except when it got cooler temperatures and quickly went down hill from there throughout the winter. Luckily the speed didn't stay together long enough to have left that transmission fluid in there, but the 8 wasn't so lucky.
I think I'm going to try to keep the car at 20psi and keep the 440's, but if that won't cut it, I suppose I'll get 565s.