keyconfig allows you to change keyboard shortcuts in Firefox.keyconfig adds the ability to create new or modify existing shortcuts defined by a element, but only changing those which itself call a function has an effect.
For firefox 3.5,download the latest version from:
http://mozilla.dorando.at/keyconfig.xpi
Edit “install.rdf” file in XPI and make a change like this:
change:

http://mozilla.dorando.at/keyconfig/update.rdf 

into:

https://mozilla.dorando.at/keyconfig/update.rdf

and change:


{ec8030f7-c20a-464f-9b0e-13a3a9e97384}
2.0.0.17
3.1.0

intoļ¼š


{ec8030f7-c20a-464f-9b0e-13a3a9e97384}
2.0.0.17
3.*

Now,install this extension and restart firefox.Click to Tools->Keyconfig,customize shortcut keys in this screen:
keyconfig