Leafsrule, you need to be a bit more specific about what is the current state and what you are trying to do or check.
With the battery charged fully the truck should power up, the engine should turn and start since the alternator only start charging once the engine is actually running.
If the belt is off and the alternator it out I personally would not mess with it. You have the charging cables hanging in the engine bay, the main power cable is hopefully disconnected at the battery or in the engine bay main connection point. In this state the truck will not run.

- Was the battery charged and the alternator diagnosed to be bad after starting the truck?
- Was the alternator taken out then and you are waiting for a new one (in this case you have the cables disconnected and the truck will not run)?