Actually, if the model has a 4WD version in its country of origin... you can still fight for it.
I have many friend of converted their Galant E33A (originally 2WD) to 4WD legally amd because believe or not, there are 4WD N/T Galant E33A in Japan! Only in snowy countries such as Japan, US or Europe.
In fact, I even found one original E33A with 4WD in Malaysia. Only one... owner flew all the way to Nagoya, Japan to buy it. Cost him over RM 100k (inclusive tax + transportation + insurance).
So, basically, you need 3 things:
1. Source the rear cut - damn rare!
2. A qualified foreman to do the conversion
3. Total inspection by Puspakom and JPJ
All these can be done legally without going through runners or 3rd parties. I've plan to convert mine when the time is right.