Firefox 3.0RC1
Step1: Find the addons file (*.xpi) and download it to your PC.
Step2: Unzip the xpi file.
Step3: Edit install.rdf and change the maxversion to 3.0.
Step4: Zip all files into *.zip and change it to *.xpi.
Step5: Install the new *.xpi by open file... in Firefox menu.
gmarks-0.9.9-fx
URL: https://mail.google.com/mail/?ui=2&ik=bcbfa2d058&attid=0.1&disp=emb&view=att&th=119f49a96c91b940
firegestures-1.1-fx
URL: https://mail.google.com/mail/?ui=2&ik=bcbfa2d058&attid=0.2&disp=emb&view=att&th=119f49a96c91b940
gladder-2.0.2.1-fx
URL: https://mail.google.com/mail/?ui=2&ik=bcbfa2d058&attid=0.3&disp=emb&view=att&th=119f49a96c91b940
simplemail.2.66
URL: https://mail.google.com/mail/?ui=2&ik=bcbfa2d058&attid=0.4&disp=emb&view=att&th=119f49a96c91b940
