M860? The M's Model number is LGMS690.
Oh and setCPU will let you go over 600MHz but only if your have custom recovery for M installed and then flash asadullahs ROM Zero, and getitnowmarketing's OC kernel and getitnowmarketing's stagefright enabler.
So you'd need to follow this checklist:
you
Make sure you're on 2.2 and not on 2.2.1
Make sure if you're on 2.2 you're rooted
Make sure you have getitnowmarketing's
Custom Recovery MS690 Optimus M
Make sure you have asadullah's
ROM zero 1.1
Make sure you have Getitnowmarketing's
GNM Optimus M beta kernel
Make sure you have Getitnowmarketing's
thunderc_m_enable_stagefright.zip
Install the custom recovery using the instructions that are on the first link.
Place "11311zerorom.zip" on the root of your sdcard
Place "signed_thunderc_metro_beta.zip" on the root of your sdcard
Place "thunderc_m_enable_stagefright.zip" on your sdcard
Boot into recovery.
Select "Wipe" and then select "Wipe all userdata"
Go back and select "Flash zip menu" then select "Flash zip from Sdcard"
Select "11311zerorom.zip"
When it's finished select "Flash zip from SDcard" and select "signed_thunderc_metro_beta.zip"
When that's finished select "Toggle Signature Verify" and make sure it says "Verification: Disabled" at the bottom of the screen.
Select "Flash zip from Sdcard" and select "thunderc_m_enable_stagefright.zip"
When that's finished back out to the main menu and select "Reboot system now"
Now your phone is ready to use setCPU.