Assigning fixed letter to burner in WinME?

Hello
I have the old HP CD-Writer 7200, external.
Since it is an external drive, sometiems it is connected, sometimes not.
My problem is, when it is connected, it takes the first available letter after the hard drives, so it shifts the letters of my CD-ROM & DVD
(i.e. without burner, it is E for CD and F for DVD... once burner comes in and takes the E, CD becomes F and DVD becomes G).
This is annoying because many of the games hardcode their .ini files with CD drive letter, whenever I connect/disconnect the burner I have to edit them directly.

I know there's a way to assign the letter to the burner, because I did it before on my last computer with Win98. I don't remember how to do it anymore on my WinME/Win2000 double boot (WinME instructions would be sufficient for now

I think I may have messed with lastdrive variable in Autoexec, but with WinME I don't have that anymore.

Any suggestions? I want to map the burner to last available letter, either G (after all the regular drives), or maybe Z to be on the safe side.
Thanx!