India can't issue International Driving Permits, permits are issued by the respective countries. Insted you have to order International Driving License or international translation of driving licence.
Transport department can issue Driving Licence for Driving in India(he has indian residency) then you can be issued International Driving Permit.Atleast the link says so.Talk to the Transport office where your licence was issued. Driving License and driving permit are not the same. Driving license gives you the authority to drive a kind of vehicle clearly mentioned in the license. It is issued for driving that particular kind of vehicle, i.e. with a driving license authorizing you to ride "MotorCycles with gear" does not authorize you to drive "Light Motor Vehicles".
Permit is issued by local governing body authorizing you to reach and roam around in certain places mentioned in the permit by whatever modes of transport, be it walking, biking, riding or driving. For example: Indian Government can issue you a Driving License to drive in India but can't issue a permit to roam around in Nepal. That permit/visa you will have to take from Nepal Government/Competent Authority.
AFAIK upon entering Nepal you will be issued a temporary registration number for your vehicle (maybe a temp DL too, not sure). And as Shamik has pointed out, if you show an Australian Passport along with an Indian DL it will only complicate the matter. Best is to contact the Nepal Consulate and sort out all things with them, if possible in writing.
International Driver’s License is an official translation of a national or domestic driver's license, which allows the motorist to drive in different territories without experiencing difficulties with various language barriers. This International Driver’s License, however, is valid only with the original driver's license, which must be currently valid and not suspended or expired. The International Drivers License also indicates that you are a holder of a valid drivers license from your country, fulfiling the right for a person to drive in another country when accompanied by an original and valid driver's license.
Prinable application for order international drivers license or international translation of drivers licence: IDLDOC.pdf (79.64 kb)