XSpell 1.0 " is a new scripting addition for AppleScript, that lets you have access to the built-in spelling system of Mac OS X. I've briefly tried it and you can use it from SC
here is the start of a function:
function asSpellcheck pWord
get script(do,appleScript,merge("check spelling of ``"))
get replace(it,comma & space,CR)
delete first char of it
delete last char of it
return replace(it,quote,empty)
end asSpellcheck
That returns a list you could then use with ask list. Needs some work.