Installing 9.1 without re-partitioning hard drive

[leeoliveshackelford at surewest.net]

Good afternoon, FreeBSD enthusiasts.  I am attempting to install FreeBSD 9.1 on a dual-boot configuration with Windows XP.  I am using bsdinstall.  I do not wish for the partition table to be changed.  How do I instruct bsdinstall to skip the re-partitioning step?  It gives an error message that it cannot write a certain file because the medium is write-only.  Any suggestions would be appreciated.  Yours truly, Newby Lee