How to run latest or multiple firefox release on linux

I want to run firefox 5 and firefox 6 on my ubuntu lucid while running firefox3.
Use follwing step,

1. Download firefox 5 and firefox 6 build from mozzila site.
2. then extract tar file and start the firefox using command 
3. start firefox5 using,

   #ff5_dir/firefox -P "ff5" -no-remote

4.  start firefox5 using,

   #ff6_dir/firefox -P "ff6" -no-remote

5. firefox will prompt you to create new profile give name ff5 for firfox5 and ff6 for firfox 6, after creating profile uncheck option "Don't ask at starup",
6. Now use the same step 2 command to start firfox 5 and firefox 6 or you can create shortcut with above step 2 command