Most of that is already possible.
Just try this in your spec bindmap:
Code:
bind mouse1 "toggle chase_active"
bind mwheeldown "+attack"
Unfortunately mwheelup does not go to previous player, is there a command to do that?
And you have to manually activate that bindmap (unless you put it on the end of your spec and play aliases).
Edit: By default mouse1 is +attack and mwheeldown is wepprev, the ideal way of implementing this (imo) is making wepprev and wepnext change which player you spec, and +attack toggle 3rd/1st person when specing.
(Idea stolen from Mr. Bougo. Hehehehe)