You might try doing what computer manufacturers do and look for heat sinks
to put directly on the ceramic IC package. An easier idea would be to go
hit a PC component place for an appropriate sized cooling fan to install
with screws straight into the top of the heatsink fins (a-la CPU heatsink)
to force air into it.

Like in my picture, http://www.geocities.com/scott_unit_69/fans.JPG
where the air is being blown into the fins to draw heat out quickly.