Tim,
No, it doesn't - you still have to do the full number of hours. A CPL will get you a few hours off, but not an IMC rating.
However, it will (ironically) get you time off an FAA IR. The FAA IR consists of (I forget the exact number of hours, but) a minimum of X hour of instrument flying, of which Y must be with an FAA instructor on an approved course, but the rest (about 20 hours I think?) can be any instrument time at all. Including your IMC rating, your instrument work for your PPL, or post-IMC rating actual IMC time, or simulated IMC time with a friend as safety pilot. To convert your FAA IR to a JAR IR, you will need a minimum of 15 hours (as well as the IR or ATPL exam credits, of course).
So if you've got an IMC rating, and you're looking to upgrade to an IR, then getting an FAA IR first and converting is probably the way to go.
The source of confusion is that an IMC rating did get you time off a CAA IR, but not off a JAA IR.
FFF
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