Went for my first ride last week. Hit 600 miles today - all canyon carving (Mulholland and Angeles Crest).
Practice practice practice.
Now I can rev match downshift just about every time.
Here's how I learned: best two video's I've seen on the 'net thus far.
(First video = aural goodness!)
(Second video - actual explanation.)
Hope they help, and good luck!
ZX10r sportbike fast downshifting w throttle blip / rev-match Part1 - YouTube
How To Downshift While Rev Matching - YouTube
Great vids, thanks!