Hey there, I live in Denver and Denver Health - the 777 Bannock St info that Herbavore posted, is a great resource. They have a methadone clinic and I know for a fact they treat IV users because I am in the Suboxone program there. ARTS too will treat IV users and they are taking people now. You just have to go to an intake appt and you should be good. Both of these are located downtown. What part of Denver are you moving to? There are way more resources downtown or centrally located here. There are very few in the suburbs but no matter where you move, downtown is about 30 minutes away driving time. Good luck!
Also - have you considered Suboxone? Denver Health is taking people now, from what I heard last, and if you have Medicaid it is covered 100%. Methadone is also covered by Medicaid here.