The SCO xterm terminfo description is not compatible with the xterm
in the R5 distribution.
To use a Bus/Keyboard or PS2 mouse you should configure the mouse drivers
using 'mkdev mouse'. You may then use the
OsMouse option in your xorg.conf to specify that X
should use the SCO mouse drivers. To do this, set the Protocol to
"OsMouse" in the Pointer section of your
xorg.conf file. You can also use "OsMouse" for your
serial mouse, especially if you are having trouble getting your mouse to
work using the X mouse drivers.