Hey jens...
Take a 1" diameter wood dowel...glue very coarse sand paper on it...this works wonders...it gives you some leverage to really hit certain spots as opposed to a sanding block...
also, rubbing alcohol is the shit for cleaning rubber...
on a side note, any of you clowns ever do the an old smith rock trick to new shoes? Where you rebevel w/ a taper and then slightly round the edge of sole...its the shiznet for small tuff edges...