I got some pretty good answers to a similar question regarding EA R'lyeh in this thread:
http://www.shrapnelcommunity.com/thr...b=5&o=&fpart=1
That said, your slave mages are amphibians. It's only the Aboleths and the Polypal mothers(sp?) who are underwater only. The best solution I have found is to take atleast w1a1 on your pretender so you can make him forge the amulets. So without starting a new game you need to empower a slavemage or mindlord.