pg_dump on Hot standby : clarification on how to

I would just like to get some clarification from the list on how to do a
pg_dump on the slave in the face of "canceling statement due to conflict
with recovery".
The following links seem to indicate that If I start an idle transaction on
the master I should be able to do the pg_dump, but I tried this in psql on
the master "start transaction", and was still unable to do a pg_dump on the
slave at the same time.
Is there something special about using dblink that would make this all work?

---->
http://postgresql.1045698.n5.nabble.com/Hot-Standby-ERROR-canceling-statement-due-to-conflict-with-recovery-td3402417.html

One solution is to begin idle transactions on the master by using
e.g. dblink from the *standby* to the master before you start *pg_dump*
on the *standby* and end them after *pg_dump* (or whatever) is finished.