@freemo that's actually not often an issue unless you're in a tech-support role or something where you're working on lots of different people's computers every day. If it's a computer you use enough to have your own account on, you can save your preference for Dvorak there. Then it's just a case of building the muscle memory so you can touch type properly - the physical keys will say QWERTY but you'll type on them as if they were Dvorak.
For background, I've typed exclusively Dvorak for essentially my entire adult life, but I never learned QWERTY properly to begin with - at my school, the accelerated program taught slideshow/spreadsheet skills instead of typing. I guess they assumed that we'd be bigshots and all have secretaries or something, but that was no longer true when I got to college, and, being the nerd I am, I decided to teach myself to touch-type Dvorak. My method was to have the keymap overlaid on the screen and not switch around my keycaps, so I wouldn't develop hunt-and-peck habits the way I had with QWERTY. First week I relied on the overlay, second week I used my memory and trial-and-error when I forgot, and then my third week was on this horrible ancient system where backspace cleared the whole damn line instead of the most recent character, so it was really punishing to make a mistake.