I guess this could be a good treatment for people who have severe symptoms. Or maybe they can find a way to prevent the hallucinations or create a similar drug without those effects. Otherwise, it seems like the person would be injected every other day and lose most of that day to side effects.
It is possible. You simply drink extract of the vine in small doses. As westerners we are a little obsessed with the hallucinatory effects which comes from the chacruna (leaf). The spirit of the medicine comes almost entirely from the vine. A drop of extract of banisteropsis caapi in water in the morning often provides more gentle results without the hallucinations.
Vaporized DMT lasts about 15 minutes. Orally ingested DMT+MAOI lasts about 4-6 hours with hour 1-3 being the most intense. In terms of this study I'd be interested to see if there's a difference between the two.