Hello devilfish..
Here is how i did it.
1) In a small bottle i put Propylene Glycol 90% and 10 % water. I shook this well so that the water was mixed with PG. (The solution looked cloudy after this)
2) I got "Gudang Garam International" cigarette and pulled out all the tobacco from one cigarette and put it in the bottle for about 2 days... I shook the bottle every now and then.
3) I take this liquid and mix it with glycerin/PG and put it in the cartridge.
You can use some flavour with it as well. It works pretty good with Vanilla and coffee flavor.
I tried this with normal tobacco and it tasted horrible (like raw tobacco). Its just this perticular brand "Gudang Garam International" cigarette tobacco that works.. If you are in asia, i am sure you should find the brand at local stores. One pack would last a year
HTH . cheers.