Hi Tim,
Funny enough, I've just done this - check out my thread for some of my experiences rebuilding the whole suspension:
pulling springs/shocks on my gt. And I'm no expert mechanic, so if you aren't, don't let that stop you.
Essentially, get the rear (or the whole car, if you like) up on jackstands, support the axle with a jack, and I think you should be able to undo the Watts linkage just like that - it's not under tension or anything. I pulled the whole axle and gave it to my mechanic - if you don't have a press, you may want to give the Watts linkage to yours. Good references for the Alfetta include the Haynes manual, plus there's a factory manual and one from Autobooks (I think), all of which appear on eBay from time to time.
Good luck!