FWIW I think
3-button mice transmit the middle button as a simultaneous
press of the other two, so that ought to work on a 6150.
Unlikely, certainly the ones I've come across don't. You may be
thinking of two-button mouse operation under Linux; the driver can
There were some that did, though I haven't dealt with ones that
did that in a good 15 years. But I remember at the time figuring
that's where the XFree86[1] guys got the practice of emulating the
middle button.
BLS
[1] I don't think it was in the MIT X11 distribution, but I don't
remember for sure.