How to install new font on OS X to be used across OpenOffice, iWork, OfficeForMac, mail and other word processing applications?
I usually use RightFont to install my fonts, maybe it can help you.
To clarify gentmatt's comment, you download the
.ttf file, double click to open it, then a new dialog shows up with some examples using it, click "install font" in the lower right hand corner, and you're done.
This installs it "for the current user" into your ~/Library/Fonts folder.
Most applications seem to pick it up and use it "next time they refresh the screen" (instantaneously for some), but without restart anyway.