Rated 5 out of 5 stars

by quad on Jan. 23, 2010 · permalink

for firefox 3.6 try this:
open the .xpi file as a .zip file (e.g. by renaming the file) and open 'install.rdf'. update the entry max version to 'em:maxVersion="3.6" '. save the file and rename it back to .xpi and install.
et voilà, works fine.