Hey Locoboy, I have quite a bit of experience with oral an intranasal Mapacho liquid and feel confident to share my experience on the ways of using this great medicine.
As in your case i found myself relapsing many times into a tobacco addiction and actually the only thing that has help me staying smoke free is eating one 2mg nicotine longizene one every two or three days, I do a lot of artistic work and without some nicotine in my system my concentration levels decrease drastically, i know is stupid.
I didn't found the Mapacho liquid to help me quit smoking as it provides a very different experience, but i indeed found it really therapeutic.
It all started years ago in the Ecuadorian amazon, I spend some time with the Quishua tribe and they took this liquid for many ailments, praising its power as an antibiotic and anti-parasite. The traditional way of doing it is putting the mapacho in a small gore (you can use a shot glass or small glass) and filling it up to the level of the tobacco with warm water (start with cold water for your first trial) and is let to step overnight. The next morning a small amount of the liquid if loaded into a birds peak (you can use a spoon, please start with little liquid on your first trials) and is taken by mouth and/or drink through the nose and swallowed. I prefer the nose route as the effects come faster and the experience tends to be more intense and clears the sinuses pretty good. As you can read they do not measure doses the main indication is to ad water up to the level of tobacco in the cup. As you are a usual nicotine user your tolerance should help you not to be over powered with the experience, it is a somewhat risky practice so please be very conservative with your dosses until figuring out how you react to it.
At time i have done this daily with no ill effects, expect maybe some nausea and lost of coordination at higher etheogenic doses. Please be very careful is a beautiful medicine but it needs to be treated with upmost respect. It will make you dizzy but at the same time provide a nice stimulation (more so than smoking) and it will kill bugs through out your system, this is common practice in the jungle. Hope this info helps you!