Yes you can do this. You can use CSVIMPORT.EXE on the core server to import the list of machines.
If you do this, you can try to send an OSD job to these machines (they will fail since they aren't on). If your machines come in configured for PXE boot first, then they will boot to PXE, see a job was sent to them that has not completed, and then they will perform that job.
You will need a PXE rep for the remote subnets though.