You can override the deployment type specified in the CustomSettings.ini file of MDT 2010 when you run LiteTouch.vbs from the command line. For example, let's say the CustomSettings.ini file of your deployment share has the following line in it:
Then let's say you want to do a one-off Refresh Computer LTI deployment. Instead of modifying your CustomSettings.ini file, open a command prompt on the target computer and type the following command:
This will start the Windows Deployment Wizard on the target computer and will override the NEWCOMPUTER setting on the MDT server to perform a REFRESH install instead.