I don't think it'll get very far in easy68k, but you could write an app that'll open the driver, then trace through it using macsbug... But that will only get you through the open routine. The Control and Status routines each key off the csCode element of the ParamBlock structure, a pointer to which gets passed in A0 (DCtlEntry structure pointer is in A1, return value in D0), so you pretty much either need to disassemble those routines to figure out what values get passed in and what they mean, or set a macsbug breakpoint on those routines and fiddle around with stuff until they get called, then follow them through.