Another possible way of doing this is to modify the sequence number (seq_num in the [synchronise] section of config.ini) on the player after emplode has been opened. If I remember correctly, the sequence number mismatch would not allow a sync via emplode. The emplode software looks to see it has the right sequence number. If they do not match, emplode will fail to update the player.

It was originally put in as a protection for multiple copies of emplode being opened via the network at the same time. Apparently, the folks in Cambridge were hacking each others' players... This would effectively put emplode into "read only" mode. Crude, but it should work.