Windows services in maintenance mode in SCOM 2007 r2 (Automate by using powershell script)

Hello,

I am using SCOM 2007 r2 in my environment. I am performing a daily task by placing the 20 services in maintenence mode in difference timings each. These services are created in windows service template monitor.

Please help me how to automate by using powershell script.

Thanks,
Chris