Normally, it will show up on fdisk as a "NON-MSDOS" partition. Just enter its number and it will be re-writable upon reboot.
Since we are on the topic, there is a way to write an "M$ fdisk blocker" using Solaris 8. I did it at my M$-cocksucking "Visual Studio C++ NET is what you will be using on the job" after-I-got-ass-fucked-by-paying-up-front school, when I finished my last, and only, UNIX class. I did it on three removable harddrives, and from what I hear, they are having a bitch of a time installing RedHat 7.2 due to a "certain student's modifications" on their harddrives. I am too drunk right now to remember how I did it, but it is in my Solaris 8 book (Osbourne.) If I am sober tomorrow after golf, I will post my solution to the problem of UNIX formatted drives being re-DOSsed.
Unless someone posts it first.....either way it is fuck M$.