An enquiring mind needs to know.
Make that two enquiring minds :)
I guessed that there must be some DMT analogue in the poison and a quick check on the wikipedia page reveals that it does actually have 5MeO-DMT. I had memory filed away that says that DMT isn't orally active unless you combine it with a Mono Amine Oxidase Inhibitor (MAOI). Apparently people in South America used to combine Ayahuasca (which contains DMT) with a MAOI (harmaline). I checked and 5MeO-DMT works the same way.
The other possible active ingredient is Bufotenin (bufo from the toad's family name), but it appears that there isn't really very much of it in the poison. It's apparently similar in structure to DMT, so chances are that it's also not orally active without a MAOI.
MAOIs themselves can have side-effects and contraindications, so I wouldn't try them without seeking medical advice.
One other interesting thing I turned up is that DMT-like drugs are metabolised by the cytochrome P450-2D6 enzyme and some people (around 6-10% of Caucasians) aren't (well-) equipped with this enzyme. Not being able to break it down could result in a much longer trip than you'd want (though there may be other metabolic routes).
So in summary of the purely chemical aspects, licking probably won't work without a MAOI, but if you can extract enough of it it and smoke it you should get an LSD-like hallucinatory high (LSD binds to the same receptors).
I'm sure all of this is probably covered in TIHKAL, but I could never justify buying my own copy :)
(Actually, I found this link)