I have installed Tiger several times with a supported Mac (in my case a Sawtooth G4), then put the drive back in my Lombard without issue. It can run Tiger without changes, but the installer won't run directly on it.

Doing it this way you avoid any issues with XPostFacto. The only time I used that software I tried to put Panther on a Beige G3. It worked once, then the office had a power glitch. Panther and XPostFacto refused to work after that on that computer.