Door-slam: Go away. Leave me alone. I have told you that we are finished being *insert relationship here*, therefore we are done, and we will never be *insert relationship here* again because I am holding to this decision until I die. Even if I don't feel as bad in a few years, I will stand by my word.
Time out: I'm fading out of your life, kind of sneakily, for a while until I feel better about being around you. I'm not going to tell you that I need a break, but the break will happen. It's for the best. Please go on living your life, and I'll decide if I can return to it.
From what I have observed of a close INFJ, the difference is:
Doorslam: I am completely done with you. No more. Please stay away from me, and I will stay away from you. Permanently.
Taking a break: I need time away from you to sort my feelings, think for/be myself, or I am overwhelmed by you. I am unsure, or I just need a breather until I can think clearly and recuperate. [In serious cases this is sometimes but not always a prelude to the doorslam.]
if there is a timeout, due to life being overwhelming, and because of that I'm overwhelming - read: perhaps some misunderstandings happened.... What would be the best way for me to stay in touch / reconnect / show I care / give you space...
I would say ask if they need space and tell them that you will give them as much as they need. Offering them that openly and willingly helps alleviate the guilt of pushing someone back and lets them know you care about them personally and that you don't want the friendship to end.