Actually this is kinda funny, just yesterday i was trying to do the same exact thing, after many hours i finally got my setup just right. i am currently running my computer in 1600x1200 resolution, while eq(i use eqw) is in 800x600 mode.
1) Make 2 Everquest Directories 1 for normal/1 for 2boxing
2) Make As many eqw directories as accts u will be playing at once.
3) Download
MiniVert2box
4) Unzip UI into your EQ/Uifiles/Mini Directory
5) Play EQ and Enjoy
6) Also i have found this
EQ Preformance Tweaks to be helpfull.