Fleximold has a great alphabet mold just the right size that Brambleberries sell but since that's out,there is freehand cutouts or a alphabet chocolate mold which you should be able to get a cheap one from any cake & chocolate supply shop or from your local craft shop.
The way l would do it is :-After you have got your letters done you just need to pour a small layer of clear ,give your letters a good spray of alcohol then set them in the clear before it dries , then do a final pour over the top of the letters not forgetting to spray with alcohol in between layers and also make sure you are using non bleeding colours..
Here is the link to the tutorial
http://soap-queen.blogspot.com/search?q=initials you would use the same technique only a lot smaller letters.Its going to be very fiddly with small letters.
_________________
Pauline
http://www.facebook.com/SudsandKissesSoapsFounding member & admin of Melt & Pour Soap Crafters.