I'd suggest that a group of people who are proficient at lucid dreaming collaborate on this (I plan to once I improove) and attempt to share dreams nightly. Like you said there would need to be a third party to recieve the findings of the two (or more) participants and compare their results. I'm not sure if distance is a factor or not because so little is known about sharing, so there would need to be close groups and seperated groups. Couples would be the key to the close groups but they couldn't talk to eachother upon waking, they might even need to sleep in seperate rooms. Anyone could be in a seperate group.

My hypothesis is that the seperate groups could be as large as the number of people who volunteer for them. The close groups are the ones that the most ground will be broken in because there are less factors involved and the participants will know eachother more intimately (i.e. close friends, relatives, lovers etc.).

I think it would be difficult to hone in on eachother if you don't know the person very well and are on different sides of the globe, but then again little is known about this and distance may not be a factor at all. Experimentation will be the key to finding new questions to be answered and new answers to the questions we have. All that's really needed is volunteers and a set regime on where and how to "meet" eachother, which I don't have a clue where to start on that path since there are no maps in dream world.