Code:
alias "downonce" "invprev; unbind mwheeldown; bind mwheelup uponce"
bind "mwheeldown" "downonce"
alias "uponce" "invnext; unbind mwheelup; bind mwheeldown downonce"
bind "mwheelup" "uponce"
bind "w" "+forward; bind mwheeldown downonce; bind mwheelup uponce"
Modified squeeks code so you can go back and forth between next and previous, this will work with fastswitch. Feel free to change the bind "w" to any key you hit a lot and remember to hit it after each switch.