Hi Norma,
When ordering overseas certificates from the GRO, I seem to remember that most if not all of the reference is in a free-format field, so the information you need to give them is as follows:
Index to Consular Births 1961-65; Consulate - Wegberg; Volume - 59; Page - 1039
I don't think the overseas section at the GRO is quite so pressurised as the England & Wales section, and they're not so strict about the format in which information is entered. The above, plus the name, should be sufficient.
Chris