Actually heroin only became illegal in Australia in 1954 - and it was used in hospitals until supplies ran out - in the 70s! I've spoken to several midwives who administered heroin to women in labour (now they use pethedine) - they all say heroin is better than pethedine because it doesn't reduce consciousness/mental clarity as much...
In terms of the original post - I think it would be very diffilcult to get prescription heroin across the line, but it might be easier to look at some other opiate in injectable form . I've seen some reports on the original Merseyside project in the UK - apparently injectable methadone was offered alongside heroin (injectable), and no preference was shown for one over the other. However, when methadone became available in oral form only, people then showed a preference for heroin....