If you're not adding custom code to the generated code, why check it into sourcecontrol? You just need the .lgp file in sourcecontrol or other versioning system and that's it.
As with all code generation based material or other large project changing systems: it is best if these actions are scheduled. So if someone decides to generate the code again, it should be done in such a way that the other project members aren't affected by it. So either add the generated code to a separate solution of which you reference the compiled form in your own code, or make sure a single person generates code at a given moment.
The reason for this is that you then avoid having to solve merge conflicts when multple persons try to alter the same file(s).