How do I get my 2-button mouse to emulate 3 buttons?

In Solaris 8, "kdmconfig" will autodetect a two-button PS/2 mouse, so
you may never look in the "change pointing device" section.
You need to go in there, and change it from
"PS/2 Mouse (2 Button)" to
"PS/2 Mouse (2 Button+100ms 3 Button Emulation)"

[Thanks to Philip Brown]