Install Subclipse in Eclipse 3.5.1 Galileo

Help -> Install New Software...

Work with: http://subclipse.tigris.org/update_1.0.x
Click [ Add... ]
Name: Subclipse
Click [ OK ]
Check 'Subclipse Plugin' in the list below
Click [ Next > ]

Click [ Next > ]

Mark that you accept the license agreement
Click [ Finish ]
If it warns you about installing software with unsigned content, click [ OK ]
Click [ Yes ] when it asks you to restart Eclipse