Rated 5 out of 5 stars

FF3:
Download googlebar-0.9.15.11-fx+ns.xpi
Unzip & Edit instal.rdf
Change line 54 "2.0.0.*" with following
"4.0.0.*"
save install.rdf, zip it in googlebar-0.9.15.11-fx+ns.xpi,
Open FF3, Files, Open files, choose googlebar-0.9.15.11-fx+ns.xpi

This review is for a previous version of the add-on (0.9.15.11).