Install Nircmd in Windows

Next button

nircmd sendkey 0xB0 press

Previous button

nircmd sendkey 0xB1 press

Play/Pause button

nircmd sendkey spc press

Stop button

nircmd sendkey 0xB2 press

Volume down

nircmd sendkey 0xAE press

Volume up

nircmd sendkey 0xAF press

Command reference:
http://msdn.microsoft.com/en-us/library/dd375731

Install Nircmd in Windows

Next button

nircmd sendkey 0xB0 press

Previous button

nircmd sendkey 0xB1 press

Play/Pause button

nircmd sendkey spc press

Stop button

nircmd sendkey 0xB2 press

Volume down

nircmd sendkey 0xAE press

Volume up

nircmd sendkey 0xAF press

Command reference:
http://msdn.microsoft.com/en-us/library/dd375731