I saw video on Youtube Where a 6" bench vise was wheeled up to the cottered crank on top of a Skate board. It was at the perfect height and allowed for removing or installing the cotters without either stripping the bike or needing to support the sideways mounted frame. I acquired a cheap indian-made bench vise for just such occassions. In the past, I have also used a "heavy-duty" 'C' clamp (the kind that require a wrench to tighten), with great results. Of course, in both cases, a socket is needed to complete the arrangement.