If the CPU is a nonPPC type- being amd64 or ix86- then you can resize with a live CD and determine the exact file type.
I've been following this guide
attempting to triple boot vista, some linux kernel i haven't decided upon yet, and mac os x, the problem occurs when i attempt to create the linux partition, with the terminal command
sudo diskutil resizeVolume disk0s2 60G "Linux" "Linux" 17G "MS-DOS FAT32" "Windows" 15G
It says that "Linux" isn't an accepted file format, which I read on some forum only happens in leopard, so I'm wondering what kind of file format linux needs to be installed on, I've been reading around but I'm still fairly confused about it.