I can't seem to find replacement cue faders for ETC's Expressconsole (not the knobs) so if anybody knows where to find those let me know
If I just took two channel faders would that work?
While I'm almost certain that it's a common (and cheap) off-the-shelf part, linear potentiometers can be a bit difficult to source just because there are so many styles and values to choose from. Have you called ETC? They are very helpful with these kinds of requests and probably have the part in stock. If you can locate the part number or suitable substitute, Mouser or Digi-Key will probably be your best bet.
Call Tech Support they will answer you literally within 15 mins or buy you a steak dinner.
There was one time when I was hour to show time. I lost my board on a Saturday and we were a full house already. No way I couldn't put on the show. I manually charged all my dimmers while calling tech support. By the time I finished they called back and even though I knew what to do the added help and conversation of someone that knew what to do as well helped me through the process. Got it done and back up and running in 30 mins. I had enough time to go smoke a cig and stress down.
I'll echo @Amiers in suggesting a call to ETC to be sure, but the description in the link you provided states that it will in fact replace your cue faders (more formally known as Playback Sliders).
Edit: Note that it does not say it will replace channel faders for the Express. Not that this necessarily means anything, but it does imply that those two parts may not be interchangeable (in referencing the question in your original post).