The menthol is easy. TFA Menthol. Add 1 - 5 drops per 10 ml depending on how strong you like it. Finding the right tobacco... aye, there is the rub. There is a tobacco only thread here that will give you some pointers. Also check out the hangsen and inawera threads. The will be your best bet to find a suitable tobacco. Making something that gives that "real cigarette" experience is not an easy task.