Not a sketchup user but I think the c-plane will do the trick.

Effectively this 'tilts' the axis so that they are aligned to geometry rather than the standard global direction. Or as Michael puts it:

'CPlane tool (under the View palette) for setting the drawing plane. This allows you to align the drawing plane to more easily work on objects that are not aligned to the normal world axes. I'll try to post some more details about this later, it still is not quite completely finished yet.'

see this thread
http://moi3d.com/forum/messages.php?webtag=MOI&msg=1991.1

Is this what you mean, if so then it is already in the V2 beta.