Found a workaround, grab USB overdrive (also good for remapping back and forward keys of non-Apple mice), get it installed, then head to Sys Prefs and open in, in the settings tab, click the drop down menu and hit ‘new duplicate settings’. For the Application, hit ‘choose’ and go find your version of Sketchup (in Applications). Then for wheel up and wheel down, just invert the direction. (I have wheel up = down, wheel down = up, but you might be opposite, as I use ‘Scroll Reverser’ across the whole system - so I can still swipe left and right and get expected results, but scroll up and down in the way I expect it to work.) I then headed immediately to Sketchup and it worked instantly =].
Happy making
Matt