You may start by looking at the help on the record locking choices. The Tools/Options menu, Advanced tab is the user interface to the settings.
Your question is vague in that it gives no indication as to whether you need all tables locked even if an unrelated table/record is being edited.
Record lock information is maintained in the file with the same name as the database but with an extension '.ldb'. Various tools exist for reading/interpreting the lock file information but it is not trivial. The read only connections can use this information to open non updatable recordsets based on lock file indications.
Alternately, you can set a flag record if you use a form interface (on dirty) to the data and use your ADO access to query the flag record/table and provide appropriate access.
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