No no and no..
No to xylene pull in plastic bag (xylene will eat your plastic
No to freeze precipitation with xylene (dmt is too soluble in it even at freeze temperatures)
and No to extracting in a place where a flatmate/owner/co-owner doesnt agree or cant know about extractions. This is bound to end in problem, xylene smells very nastily, you might leave stuff around, and anyways I think maybe its an opportunity to think about trust issues in the appartment, not to preach on you because each relationship is unique.. But I think the fact will have to hide from your partner in many levels already contributes to this not really being a good set and setting to extract .... Also remembr you are putting others at legal risk too, so if its not your place or everybody living agrees, you're putting others on the line for your actions without their consent.... All these things attract negative results ime
Also, please read our FAQ, our attitude page and our health and safety section (and search function in general), because I think those might answer some of the questions youve been having.
Good luck