Okay, I went back to a saved game and did some experimenting. The first time you have to click on the dreamer, it appears you don't have to press the F key at all. Just click on her as she falls, and allow Zoe to miss her once. The second time, it looks as though you do have to press the F key. However, once you're pressed it once to track her, you do not have to hold it down. I just assumed you did, as that is what I was doing to make sure the scenario worked properly.
So you can press the F key when she is at the beginning of her fall, then move your hand to the mouse and click to bring up the scroll wheel. You will have to be a little bit quick - she may be closer to the bottom of her fall - but once you click on her, she will freeze, and you can press the bottom hourglass icon. When she slows down, click on her again to catch her. She will be falling slowly at that point, which should give you a bit more time. If it's hard to coordinate the first time, just try it again.
Unfortunately, I don't see any way of using the keyboard instead of the left mouse button. I tried assigning different keys to see if that could be an alternative, but I couldn't get the keys I selected to work in game. I'll try and play around with it a bit more when I get more time. In the meantime, if you think you can get the above method to work for you, go ahead and give it a try. Once you get past this part, you shouldn't have any more trouble with these sequences. There is one more section where you will have to run and close a door quickly, but you will have endless opportunities, and you can use the mouse entirely for that one. By the way, are you using the right mouse key to move around? Or the wasd? If you're not using the mouse method, you may want to try it when that part comes up. Pressing and holding both mouse buttons will allow you to run, and you can swerve the mouse like a camera while you do so.
Don't worry,
most of the game is very slow paced and allows you to take your time. There are only two sections - the falling dreamer and the closing door section - where there is a timing element involved. And none of the game requires the dexterity the original Dreamfall did.