I've had some really good look with the Synaptics TouchPad X driver at http://web.telia.com/~u89404340/touchpad/index.html
, and it has some other nice things besides the "wheeling", like having middle-click when tapping with 2 fingers and stuff like that.
It suppousedly also works with ALPS touchpads (like yours), but I don't have one of those to try it on.
Just follow most of the instructions in the INSTALL file (a "make install" does the 2nd step -actuall install- just right).
Also edit your /etc/rc.d/rc.modules file and at the place where it loads your "psmouse" module change it to read like
54 if echo $SHORTREL | grep -qvw 2.4 ; then
55 /sbin/modprobe psmouse
(e.g., remove the proto=* part. Note that I had to do this for problems with my Synaptics Touchpad, it might not be necesary for the ALPS touchpad), and also, around line 271 uncomment the command
270 # Generic event reporting device:
271 #/sbin/modprobe evdev
otherwise it won't work.
(P.S., also I just found this links which explains some stuff better than I do: http://gentoo-wiki.com/HARDWARE_Synaptics_Touchpad