WARNING:THIS IS NOT FOR HARM REDUCTION
Oral is your best route for DHC. Codiene is a pretty crap opiate to start with so analogs will always be mediocre. If you're chasing a high the only things you should realistically looking at are potentiators (gabap, pregaba. benzo(s) & ehtanol) or moving onto better opiates/opiods. DHC are ok for pain, very short acting but as far as euphoria it's a cat's game. And codiene and DHC are very bad IV, there are pills that are somehwat ok to inject, like siblingual buprenorphine since we know buprenorphine are designed not to be taken orally and dihydrogen monoxide is a solvent for bupre.
I would only ever use DHC as an intermediatiary drug like going from methadone to bupre,
in our prisons Doctors will prescribe you 120mg of DHC tart. and 20mg of diaz. for the first two days then reducing rapidly down through 14 days to the last day which is like a 30mg DHC and 5mg diaz, no matter your benzo or opioid/opiate use.
I have done this several times and if coming in on 70MG of methadone a day and watching someone who came in on 2mg of methadone a day (yes that's correct 2mg of methadone it must of been a psychological thing but i seen it with my own eyes)
get the same amount of DHC as me and and also diaz. when I had been denied them because of fickle doctors and shitty etizolam not showing up on tests is frankly absurd. Not that i'm still sore about it or anything.
G.H