to get the ABI right, just use extern(C) on the relevant D functions.

Wow, ok, that was well hidden. I'd strongly suggest that block in http://dlang.org/interfaceToC.html get its own heading.

however, if the perl interface needs to write wrapper functions based on C headers you will have to write a C header containing the relevant function declarations.

Yeah, that was what i suspected, but hoped to avoid by reusing someone else's efforts. :)