I have a macbook that I have a vista and xp partition on. I can boot into osx, vista , and xp fine. But from vmware fusion bootcamp I can only boot into vista. I get a hal.dll missing error because the xp partition is not in the bootcamp config (vista was installed first, so that's what launches xp).
How can I add the xp partition to bootcamp. I've been looking everywhere and trying to add random setting to the vmx file. Any help out there?
Adding random settings to the vmx file is not the best way to go about this! 
What you will need to do is manually create a Virtual Hard Drive for a Virtual Machine you create to support the unsupported second Boot Camp partition using information found in the following thread as an example of how to manually create Virtual Hard Drive of a RAW Disk.
In addition to creating Virtual Hard Drive of a RAW Disk you also need to add the following to the target Virtual Machine's .vmx configuration file:
snapshot.disabled = "TRUE"
suspend.disabled = "TRUE"
If you do not add the above settings you will risk corrupting the Windows XP Boot Camp partition. These setting are default in a Fusion created Boot Camp partition Virtual Machine however you need to add them wen manually creating a Virtual Machine with a RAW Disk as its Virtual Hard Drive.