Step one, make sure you have a KMS server and you have set it up for Office 2010. If not, check out my post on setting up your KMS server Office 2010.
Activating Office 2010 with your KMS Server
Open an elevated command prompt on your client with Office 2010 installed.
Change directory into your Office installation directory cd “C:\Program Files\Office 2010\”
Then change directory into office14 cd office14\
Now run ospp.vbs /sethst:kmsserver.yourdomain
The above command set’s your KMS Server (replace kmsserver.yourdomain with your server’s name)
Then run ospp.vbs /act
The above command activates your Office 2010 with your KMS server
Now close your command prompt, you are good to go.