well how about this one for starters......
This is from an instructional DVD that I recently played on for my good friend Marko Djordjevic.
http://youtube.com/watch?v=lbztoV3ezsU
in this clip he's explaining about sub divisions in 5/4 time, and how we move from a regular sounding 5/4 groove to a slower feeling 4/4 groove and how they're related.
I think one of the most important parts of metric modulation is to be in control of your subdivisions and to have all aspects of basic 16th note rhythm feeling natural as part of your playing. Once you have the basics down it's just a matter of making up odd groups of subdivisions withint the context of the time you're already playing in.
I think Marko explains this really well in the clip, and the concept he's talking about, and the ideas we're playing can be used in all meters and tempos etc....
Easy,
Janek