Is this impossible to install XP using BootCamp on Lion?
In Bootcamp: You can bypass it by putting in a Windows7 disk and format the drive for the Windows installation.
After that you just restart, press alt to bring up the boot menu and put in your Windows XP CD to install.


One way that should work aswell(havent tested) is if you just create a new empty FAT-partition and then go to step 2.