Any body? Bueller? Bueller?
We have never tried it out ourselves (the developers of Photo Mechanic.) Do they have a demo? I don't know what technologies they use to enter the text you speak, but if they do it right, you should see text enter right into various dialogs in Photo Mechanic. We don't use any custom text fields: they're all standard Windows controls so if they go through the proper channels, it should work.
HTH,
-Kirk