=item C<typedef NAME, TYPE, MEMBER, TYPE, MEMBER, ...>

idea 1:
typedef(POINTERNAME, EXISTING_TYPE)
or
typedef(NAME, TYPE, MEMBER, TYPE, MEMBER, ...) #legacy proto

with 

die "usage Win32::API::Struct->typedef( NAME, [NON_POINTER_STRUCT_NAME]
| [TYPE, MEMBER, TYPE, MEMBER, ...])" if scalar(@_) % 2 == 1 && scalar(@_) != 3; #or approx that, didn't run it