the easy way is to call sprint and ask... if thye don't give it to you activate your phone again online and they'll give you the "programming code"
Here is how to get your MSL.
Step 1: dial ##3282#
Step 2: select "EDIT"
Step 3: Type in any digit code then click OK and you should see a message said " Invalid Lock Code"
Step 4: Exit out and go to Play Store and download an app called "connectbot" made by Kenny root and jeffery sharkey
Step 5: download and install, open the app next, next, next,
Step 6: the main interface you should see " ssh, then an arrow pointing down", username@hostnameot
Step 7: tap on ssh and select local, put any nick you like
Step 8: type this command with out the quotation mark " getprop ril.MSL " then click enter and you'll see a
six digit number and that is your MSL............yeah you done it!
Note: U must follow step 1 to 3 in order for this to work ( high important "