This is a comment from the question asked. This is not a question posed from a addict but from a openminded hallucinogenic thrill seeker who believes in exhausting all methods before choosing the best suited for me
In the book DMT: The Spirit Molecule, DMT is given intravenously to subjects in a clinical research setting. So this is to say, Yes it can be injected. However, unless you have laboratory grade synthesized DMT and have a phlebotomist on hand, it is probably not a good idea to inject it. Most DMT extraction methods from plant sources are going to leave behind residues of materials used to perform the extraction and depending on the method, perhaps other alkaloids from the DMT source.