I have done the Peripheral extraction thing. You have a needle in each arm, and apart from that slight discomfort you can just sit/lie back and watch TV for a few hours. As tripa says, you get a few days of injections beforehand to stimulate the production - these are subcutaneous, like an insulin shot.

Here's some more information: http://www.beatson.scot.nhs.uk/content/default.asp?page=s22_...