I was accepted to both schools (different program) as well and have researched this quite a bit. Each website has all the information you need. Basically as far as the states are concerned once you live there primarily without any ties to, in your case mass., you're a CA/CO resident. You have to start the process of establishing residency for a full year before you'll qualify for in-state tuition. So you need things like a CA/CO license, a signed current lease in the relevant state, etc., and then your year starts. Basically becoming a "State resident" isn't too difficult, you just have to live there and no where else, and get a license etc., but residency is for tuition purposes, so you go to the school's admin office and start the process like a previously mentioned.
If you google things like "CO residency", or "CU residency", etc. you will find the right info, they all have it online. Let me know if you have any lucky, i can track down links if you don't!