I've been working on an MM7 mod. So far I have been able to make some progress with items, monsters, and respawns, mostly with Stormcat's MM7View tool (for editing lod files).

I haven't been able to find any tables in the MM7 lod files for character class skill tables, attribute tables, and ability/spell data - which I wanted to rebalance. How would I rebalance those?

Just a note: I have a byte editor/hex editor which I use for editing save files for various games. If skill/attribute/ability tables are packed into a binary file packed into one of those lod files, I can edit them with the byte editor.

Afaik some of those values are stored in the game's executable file.
Here's a thread from somebody modding the exe directly:
http://www.celestialheavens.com/forums/viewtopic.php?t=14845

Have you ever tried MMExtensions? It provides txt files for some values to make modding easier.
http://www.celestialheavens.com/forums/viewtopic.php?t=10423