Any way to fine-tune image position without the mouse?

First to explain what I'm doing: I'm placing a series of digital photos side-by-side on the Timeline, with cross-dissolves in between them. Each image shows the same drawing, only it gets more and more developed as it goes along. For this to work well, each succeeding image must be placed exactly on top of the preceding one. So what I've been doing is carefully adjusting the position of each new picture in the Canvas, using the mouse, until it sits as precisely as I can get it on top of the preceding one.

(By the way, I'm doing this by putting a cross-dissolve between two pictures, and then putting the playhead right in the middle of the dissolve, so that I can see both images at the same time. Then I move the most recent picture around with the mouse, that is, by holding down the mouse button and carefully pushing it until the two images are superimposed as closely as I can get them.

Trouble is, the mouse is not a very precise tool for this. What I'd like to do is the sort of thing you can do in Photoshop, Indesign, and other programs where you can select something (like an image or object) and then nudge it around with the arrow keys, one pixel at a time. By tapping the arrow keys, left, right, up, down, you can jog things around with great precision, which is just what I need in a situation like this, trying to get these pictures exactly on top of one another.

In Final Cut, of course, the arrow keys don't do that; they move the playhead around in the Timeline.

So my question is: when you want to move images around in the canvas with great precision, is there some way to dispense with the mouse and precisely nudge them around with keyboard keys? Or any other way?

Thanks for any advice,

Tom