Is it possible to boot OS X 10.6 from a USB drive with VMWare Fusion 3.1.3? I have USB drive with a partition containing OS X 10.6. I boot from this drive to use an app which doesn't run in Lion (Xcode 3.2.5). Rebooting is annoying.

Is it possible to boot a VMWare Fusion virtual machine directly from the USB drive (i.e. not 'forking' a virtual machine from it)? I have tried Booting Operating System from USB Drive in VMware Fusion 3.x but it doesn't work for OS X (I changed the settings to OS X 10.6 Server instead of Windows 7). I have VMWare Fusion 3.1.3.
You need 10.6 Server. It does not help to change the settings to 10.6 Server, you have to use 10.6 Server as operating system on the USB-Stick… or you can try some hacks, e.g. Hackintosh (search for it in Google) in a virtual environment but that's a little bit more complicated you can check

http://wiki.osx86project.org/wiki/index.php/Installation_Guides#VMware_Install_Guides

for this.