Ok, the alternator oil seal is leaking. How do I replace it? Remove alternator, remove flange, replace seal, done?

Yes, you are essentially correct. It's obviously easier to remove the seal from the bell housing if the bell housing is first removed from the engine block. The seal pulls out from the front and installs from the same direction. There is a circlip against which the new seal will bottom out. The trick will be getting enough leverage to remove the old seal (the alternator drive shaft will be in the way as well as the bell housing casting walls) and finding a large, deep socket to use as a driver for the new seal (again because of the drive shaft). Remember to check the resulting lay of the seal material around the shaft to make sure it is pointing inwards towards the bell housing.

Ok, I haven't gotten around to fix this. How do I remove the flange of the shaft? Things are so tight that I can't fit my puller to remove the flange.
And another thing, Is the oil seal the kind that has to be soaked in oil befor installing, it seems to look that way on the picture on the websit. (I'm buying all my parts from http://www.motobins.co.uk/ )