In that case, I'm afraid I don't know of any such program. I always edit using the mission editor.
Suggestions, in case you haven't tried these:
It should be possible to un-PBO the addon folders and take a look at the config.cpp file. This is where the class names for each unit are defined (and indeed, they should be sorted by type).
But actually, most mods have documentation containing the class names of all the weapons, men, and vehicles used. Have you looked there?
You can edit your mission.sqm file using a text editor that has a "find and replace" feature. Type in the string of the class name you want to replace, and the one you want to replace it with, and
voila.