How can I get sufficient guidance from an advisor who's always travelling?
Some possibilities:


Consistently-scheduled discussion-by-video (Skype, Google Hangout, whatever). Treat these as you would any meeting: send a good agenda in advance.
Collaborative workspaces, e.g. a Google doc where you and your advisor can leave comments to get issues resolved
A bug tracker, even if that's an idiom both you and your advisor understand
Someone else deputized to triage and help you over simpler problems, so that your advisor knows that whatever reaches them is important and/or troublesome


The goals here are to ensure that you get what you need as conveniently as possible for your advisor and as quickly as possible for you.