99.9% of time award inventory is only loaded on the operating carriers flight number. In the rare case it is loaded on a codeshare, it can be booked like any other flight with that carriers code. Since flight numbers change it would be hard to keep track of, especially considering how rare it is.
Thus the VA codeshare on HA to SYD can be booked. I believe on that one that VA actually "buys" a couple of rows. IE HA can't seat or sell a ticket for those seats, as it's VAs own seats for practical purposes.
Others are strictly loading inventory on the codeshare. Other than AF on JL flights, I know there's a few AF flights on one of the Indian ocean island carriers that are bookable.