You could set up an Edit table in your db, and as soon as someone edits a record, write some information back regarding what record it is and who has it. When someone else tries to edit a record, first do a check to see if it is the same record.

If it is, then display a message, if it isn't then let them go ahead, after logging their edit information.

When they are done with the save, you have to release the record by removing the edit information.