Microsoft has a tool to save/restore/move the user profiles:
http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=cd72250f-2e02-430e-8f99-e1acae760564
but AFAIK the format of the files involved isn't public.
When you say dictionary I'm guessing you mean the lexicon, on my system it's stored here:
C:\Documents and Settings\username\Application Data\Microsoft\Speech\Files\UserLexicons
It's probably part of the files that are packaged up by the profile tool, but I don't know that for sure. Again I don't think that the format of the lexicon file is public.
Is there something in particular you are trying to do?
John Conde