kencr, everyone...

Thanks for the help.
I hate the idea of punching a hole in the roof, but I see no other way.
kencr,
The inside of the curb is part of the exhaust duct.
I'll look at Graingers for a pitch pocket, or rubber boot-type flat flashing.

[This message has been edited by Redsy (edited 04-24-2006).]