I can't remember where I read it, but I know I saw a discussion on this topic before.  Some people were doing tests administering both DMT and 5-MeO DMT by dissolving it in DMSO and applying it to the skin.  They concluded that the required amounts for an active dose of DMT simply could not be practically administered in this way.  However, they concluded that 5-MeO DMT did work (or at least produce some effects) this way.  I believe I also read of success administering LSD this way.  Again, not sure where I read this (probably some other board) but it was a pretty thorough experimentation.