Logitech's Apple control-freak program proved as useless as most of their Beastware offerings.
Managed via Apple's limited control choices ... turned out that the middle-click [the scroll wheel] ended up where I wanted it anyway:
widget display toggle, incl. the indispensable iStat == You Need This, drook!
(along with smcFanControl, though maybe not so much as does the iMac, which needs extra cooling when ambient is Hot.)

Happy Ring-0-safe prestidigitating!