i had the same problem with extracting data from a .fig file, and came across a solution at:
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=a2k9hp%247c5%241%40news.mathworks.com
excerpt from the above URL:
----start excerpt-----
openfig('MyTestFig.fig')...