Yes. In Solaris x86 2.1, these worked 'out of the box'.
In Solaris x86 2.4, they are no longer configured during the installation, but they still work if configured afterwards by hand. Sun apparently disabled them in this way because they are no longer officially supported, but fortunately, they did not actually remove them from the kernel, so you can configure them back in yourself as follows.
First verify the device's major number with grep:
# grep -i chanmux /etc/name_to_major chanmux <num>
Add the /dev entries, substituting whatever you found with grep for <number>:
mknod /dev/vt01 c <number> 1 mknod /dev/vt02 c <number> 2 etc...
add the following to /etc/inittab (after the co entry):
v1:234:respawn:/usr/lib/saf/ttymon -g -h -p "VT1 Login: " -T AT386 -d /dev/vt01 -l console v2:234:respawn:/usr/lib/saf/ttymon -g -h -p "VT2 Login: " -T AT386 -d /dev/vt02 -l console etc...
To get init to reread inittab, either reboot, or issue the command:
/usr/sbin/init q
Now, Alt-PrintScreen F1 switches to VT1, Alt-PrintScreen F2 switches to VT2, etc, Alt-PrintScreen P switches to previous screen in cyclic sequence, Alt-PrintScreen N switches to next screen in cyclic sequence. Alt-PrintScreen H switches to console screen (and not Alt-PrintScreen F8 as on Interactive Unix)