I was having problems with sometimes being unable to answer calls with S2U2 & my current configuration may be what you're looking to achieve:
First perform the following regedits:
1)
HKCU\ControlPanel\Keybd\DeviceLockWhenSuspend = "1"
2) HKLM\HARDWARE\OEM\KEYBD\KeyLock = "0" [this allows any key press to wake up the device]
Then, install http://thewingster.com/autolockscreen.aspx
Once installed, you can configure at Start/settings/system/SmartLock
My phone is currently configured with the following options checked:
A) WM 6.5 new Lock
B) Suspend Lock
c) Incall Lock