i pretty much only play on p1999 now but if you do want to check out other servers here's the best way to do it.
first you wanna fresh install of titanium.
then for each server you want to play on you make a new EQ folder (copy + paste + rename) and make the necessary changes to that folder.
for 1999 you can fit all the necessary game files in a folder about 1.35 gigs. check out this thread:
http://www.project1999.org/forums/showthread.php?t=7186
i'm not sure if there are similar things you can do for other servers, but the entire game isn't that big so having individual folders is definitely the way to go IMO.
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the second best way to do it is to either find a loader (i know their used to be one, but it was pretty buggy and wasn't updated that often) that will swap the files you need in and out or do it manually putting all the files in backup folders. this is a pain and its easy to loose track of which files need to be swapped.
EDIT: if you have any questions about doing this feel free to PM