How to Download Firefox 2 extensions using Firefox 3 from Firefox Addons site. [HowTo]

If you have been brave enough to try out Firefox 3, you might have noticed that a lot of extension in the Firefox addons site is unavailable to you.
This is because those extensions were made for Firefox 2 and are hence not supported in FF3. So, the good folks at Mozilla have completely disabled downloading of such addons, if you browse to the addon page using Firefox 3.

We however disagree with the Mozilla developers. We have found that a large number of Firefox 2 addons function seamlessly in Firefox 3 and it is really cruel to lock out FF3 users from enjoying those extensions.

How to download Firefox 2 extensions using Firefox 3 From The Firefox Addons Site?

1. Take Firefox. Type about:config into the address bar and hit enter.
2. Click on "I'll be careful, I promise!" button.
3. Right click and select New -> String.
4. Enter the preference name as general.useragent.override and the value as Firefox/2.0.0.14

Now go to an addons page like this and see whether the "Download Now" option is enabled.

How to enable installing Firefox 2 extensions in Firefox 3

We have already covered this here, but reproducing it here for making this post complete.
Even though, you are able to download FF2 addons using the above method, your Firefox 3 will resist installing incompatible addons unless you perform the below steps.

1. Type about:config into Firefox's address bar and click the "I'll be careful, I promise!" button.
2. Right-click anywhere. Choose New -> Boolean. Make the name of your new config value extensions.checkCompatibility and set it to false.
3. Make another new boolean pair called extensions.checkUpdateSecurity and set the value to false.
4. Restart Firefox.

That's it. Now you'll be able to download all addons from Firefox Addons site and also install them in Firefox 3.