Firefox 3 beta have been released, and if you have been reading DailyGyan, you already know how to run Firefox 2 along with Firefox 3.

But Firefox 3 beta has a serious issue. Lack of extensions!
Many extension writers are waiting for the official release of Firefox3 before porting there extension to it. The result is that many of our beloved extensions refuse to install in Firefox3.

In this How To, I'll show you how to install a Firefox2 extension in Firefox3 beta using the official del.icio.us Firefox extension as an example.

1. Go to the delicious extensions page.
   
2. Right click on the Install Now and select "Save Link As". Save the xpi file to your computer.
   
3. Open the downloaded xpi file using any zip application. Inside the archive there will be a file named install.rdf. Open it using a text editor.
   
4. Change the line <em:maxversion>2.0.0.*</em:maxversion> to <em:maxVersion>4.0.0.*</em:maxVersion>
   
5. Save the file and update the archieve.
   
6. Drag the modified xpi file into Firefox to start the installation.
   

Update: LifeHacker blog suggests the following procedure.

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

(However, I couldn't get this method to work for me. Even after setting the two values, firefox was still doing compatibility check and failed to install the extensions.)

Related: Official Delicious Extension for Firefox 3 Beta
Happy Firefoxing