In case someone else gets stuck on this, you can download LazyScript, install it, click the 'UI' button, and put the required ruby script in the box at the bottom, probably best under the item 'comp'. Either this or you can download a third party ruby console plugin (not the existing sketchup ruby console).
I am working on a really unique SP project - two joysticks, over 20 different machinery functions being simulated - but I am facing many challenges given the lack of documentation and lack of SP discussion on the forum now. If anyone expresses interest I can put up what I learn about joint control here..... its quite fun and I am learning (through trial and error) many things that I haven't seen discussed on the forum.
Ash