I came across an interesting post on the SOE forums regarding switching between old-style spell effects and the current ones. After trying it out I found:
1) It works
2) It isn't a hack
3) It enables the main portions (surrounding area, floor, and target) of the old spells
4) It doesn't enable the hand effects we used to have
5) It calls the original spell sound file.
6) You have to do it every time you launch EQ.
To enable the effects launch EQ normally. After patching and before pressing <PLAY> open a file manager and delete the files-
.../everquest/spellsnew.edd
.../everquest/spellsnew.eff
Click <PLAY> and enjoy.
Every time you patch, these files are downloaded so there is no risk to the integrity of your EQ files. Switching back to the new effects is as simple as restarting EQ.
I don't know if there are any issues with this working on high level spells that didn't exist before spell effects were changed. My highest character is 65 and it seems to work with everything I've tried casting.