Probably not...
While it is using the same chipset as the Rev A MDD PowerMac G4 -- Apple added 2 PCI-to-ATA bridges, some controll panel lights, controlled cooling, PCI changes, smart drives, etc.
These changes would not be reconized by the old OS 9 ROMs, and would problematic for booting -- since the only thing in the a MDD bootROM's OS 9 ROM file lookup sequence is the CD drive on the XServe.
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People did take the old 9600 ROMs and put them into the Apple AIX server, but ran into a bunch of problems.
Most likely you'd have problems getting a MDD's bootROM hacked to boot OS 9 XServe, then more problems with the OS 9 ROM file recognizing the hardware changes.
[Edit -- You can however get Mac OS X Server (the software) running on a Rev. A MDD PowerMac, and buy the Legacy Mac new from Apple]