Pressure kinda depends on your kegging system. I used the same pressure and temperature settings I would for an ale and let it slow carb for a week and got great carbonation. After it reached terminal gravity, I let it sit for a week, then cold crashed the whole carboy for a week, then left it on gas for a week. So 3 weeks for me came out perfect.
My second batch has been bubbling away nicely since last weekend. Process on page 1, but with different materials:
1lb Caramel/Crystal 90°L
4oz Torrified Wheat
3.3lbs Briess Sparkling Amber LME
4g fresh pressed apple cider
Danstar BRY-97 American West Coast (dry) Yeast
I used Caramel 60°L the first time, but the finish was really dry and I wanted a little bit of malt sweetness in there so this time the plan was to go for Caramel 120°L. Unfortunately, my LHBS was out of Amber DME so I decided to replace all the DME with the single jar of LME above. In the past when I've used LME it always seems to finish higher/sweeter, so I stepped back to Caramel 90°L. I had a huge krausen and a blow off, but that may be due to the different yeast (US-05 vs BRY-97) and 3.3lbs LME vs 2lbs DME.
Smells great, can't wait!