You have different 5 ISO's to install, so when the installer asks for the next disc, unmount the current ISO, mount the next one, and continue. I used MagicDisc as well and it all worked fine.
Don't forget to add the extra files mentioned on the setup page. You can get updated textures (which I recommend) by following the instructions here:
http://www.project1999.org/forums/showthread.php?t=2482.
Download the smaller files making up the EverQuest Trilogy pack, not the single big one, as it doesn't work.