I believe you have already resolved your problem, but for anyone else who might be reading this later on...if the LexSpell menu is missing in the email composer after installing LexSpell (and its word list dictionary file) do a power cycle on the BlackBerry and it should appear.
Power cycle is battery out, battery in.
At least that's what we're getting during the trials.
I admit we do not have an explanation of why it sometimes works out of the box and requres a power cycle in other cases, but at least it gives a solution.
Hope this helps!