Gday Mate
The grewia is an aussie native, very easy to look after much like a chinese elm when it comes to light requirements,ie can stay indoor for days at a time and quite frost tolerant too.
Here is a site that has a little info, maybe Pup over in WA has some growing or even Leigh from Ledanta.
Regards
Eric
http://www.bonsaigardener.org/lavend...er-bonsai.html