@tinyfaery, you might not like my advice, but here it is: don’t do anything different. Your resume shows that you are employable. All the skills you have already mastered are available in a temporary setting, and if those don’t include championship typing, so what?
I type almost exactly the same way you do, including memorizing whole sentences at a time when I have to transcribe. I started writing stories on my mother’s ancient Royal when I was 7, and by the time I took a typing class in high school it was already too late. It was my way or nothing: a four-finger scramble (now up to six) all over the typewriter keyboard—nothing electronic then, of course. I managed pretty decent accuracy, considering that it was all going directly onto a sheet of paper, with no correcting keystrokes before you printed.
The temp agency insisted on testing me, and I said, “Okayyy…”
I tested out at 50 wpm and they sent me out on jobs that called for typing skills.
(But this was back when letters written on paper and sent by postal mail with a stamp were the standard form of business communication. Does anyone do that any more? Do secretaries or “admins” still take notes and transcribe the boss’s communications? Isn’t typing a completely different kind of office skill now, put to different use on computers?)
Real typists who happened to pass behind me and notice would say “I can’t stand to watch you type.” I usually found some excuse to pause, though, whenever anyone was close enough to see.
What happens if you don’t meet their minimum? You don’t quality to be sent out on jobs that require typing. Lots of jobs don’t.
You could practice enough to pick up your speed and accuracy in transcription, but I can’t see trying to master a new method that fast. Under stress a brand new skill is apt to desert you. To me it makes more sense to be hired for the skills you have than go into a job where you have to sustain skills you really don’t have.
What you could do is start a program to improve typing speed and accuracy so (a) you can say you’re working on it and (b) you’re ready for the next agency that asks you, or a later retest with this one.