To use multiple yahoo messengers machine
1. Click on start button, click on run, type regedit and click on Ok button.
2. Locate HKEY_CURRENT_USER\Software\Yahoo\Pager\Test
3. Right click on right side window, click on New and then create Dword value
4. Name it as Pulral, double click on it and give value 1 in Hexadecimal
5. Double click on your yahoo messenger icon, it will start a new messenger every time you click so you can login with multiple id's in single machine.
To use multiple gtalk messengers in single machine
1. Right click on desktop and create a new shortcut
2. Give the path of your googletalk.exe and add /nomutex at the end
Example: “c:\program files\google\google talk\googletalk.exe” /nomutex
(Depends on where you have installed your gtalk.)
3. Give a name you wish to the shortcut.
It will create new instances as many times you click on shortcut so you can use multiple id's
----Soon i'll post scripts so scripts will do all job automatically.