When i try to connect to tmi.twitch.tv port 6667 im getting this error '-tmi.twitch.tv- Improperly formatted auth'
I've tried to connect to tmi.chat.twitch.tv as well. The oauth key is being inputted correctly i believe. "oauth:" at the beginning, key after.

I had noticed other threads regarding the 7.4x changes (?) and shifted my password down to the last box. I did notice that error only started when i had done that. Previously i was getting a flat login fail. So it seems im on the right track?
Really not sure whats going on here, if anyone can help out here. I'd apprecaite it

mIRC version 7.63

I hadn't tried to connect to twitch in a long time, and I had similar trouble as you, until I finally got the combo they want. There may be other setting which also work, but I used:

address = irc.chat.twitch.tv
port = 6667

TOP PASSWORD = oath:oathstringgoeshere

login method: SASL (/CAP)

bottom password = leave blank

As I understand it, the top password is for servers that require the password before even allowing you to connect, while the bottom password is for stuff like nickserv.

Once I connected, I did get a couple of errors, but I doubt these are fatal, other than I don't have the correct CAP commands set.

USERHOST Unknown command
LIST Unknown command

That absolutely worked!

First password field holds my oauth
connecting by Login Method SASL (/CAP)
second password field empty

Up and running, thanks a ton @maroon. You da MVP