what kind of mouse for Color?

[kookooframe]

I'm learning Color through the Apple Training series. I'm using a mouse with a right and left click and a scroll wheel but I can't seem to get the fade controls to come up when I vignette a selection in the Secondaries room. I've tried clicking the scroll wheel as my "middle button" but that doesn't do it. Do I need a different kind of mouse? Or could it be a bug in Color? Is there any workaround for this if I don't have the right mouse?

I'm using Color from FCS2 on a pre-Intel PowerMac G5.

Any thoughts appreciated!