Quote from Thistlewhistler
I don't know about multiplayer, but I'm in love with Rei's minimap, and I use it with Twilight Forest, but I found that the only way to work it is to install forge, install Twilight Forest in the mods section of forge, and then install Rei's minimap in your minecraft.jar file. It never worked if I put it in the mods section of forge; I had to install it the ugly route of copy/pasting it into my .jar and deleting the overwritten files.
Hope that does something for you!
As I said above, Rei's minimap is added to the jar tab, which puts it in the jar along with forge.