Medical dictionary or spellchecker?

I'm wondering if anyone knows of a medical dictionary or spellchecker for pages? I have two for Word (Dorland's and Stedman's) - is there any way to add these where they will be recognized by Pages (or the rest of Apple's spellchecker-dependent apps?)

I use Mellel and Notebook, as well as Pages, and would prefer not to have to use Word for my writing needs. Too darn slow and, well, general uck.

Thanks!