Dead easy

Just be careful when drifting out the old races..use something like a brass or copper rod to avoid damaging the seats. Also, make sure the seats are nice and clean before installing the new ones, drift the races in using something that won't mark the faces if you slip (or a proper drift kit...I use a Facom one and it is excellent)

Use pleny of the correct grease and tighten them up as the book says...takes about 1-2 hours per side.

Cheers
ant