FAQ? how best to implement locking with MS Access client, Postgres server, and ODBC?

I have read all available documentation I can find, and am struggling to
understand how best to implement locking in a multi-user database using
Access 2000 as the front-end.

Here's the current scenario.

Postgres has the default "Read committed" mode
Access is set to open in "shared" mode, with "record-level locking".
ODBC has row versioning turned on.

I have two machines which attempt to modify the same record in a form.
The first succeeds, the second fails & rolls back and then the Access
application throws up a "no current record" error.

I can trap that error in the Access application, but what then am I
supposed to do with it? I'm happy to either retry the update, or drop it
silently, but can't work out how to do either successfully.

I guess I have two questions:

(a) has anyone got locking to work in this environment? if so, how?

(b) where can I find some more documentation on this? I've googled for
hours, but haven't found much of use.

Any pointers will be most welcome...
Rachel