Yes, if you're mechanically inclined it's not a very difficult adjustment. My credentials - 18yrs at Ford corporate, about 10yrs of that in advanced manufacturing on F150 (almost identical front end as Expedition). I was responsible for designing the automation that set the alignment in the factory.
If on a flat road (no crown) you can let go of the wheel and it tracks straight, but your wheel is off-center, it's probably a clear vision problem (weird name, but that's what they call the perception of steering wheel being centered). Let's say for example your wheel is off by a few degrees clockwise. If you move the steering wheel to center, both of your wheels will now be steering slightly left. So you'll want to rotate both wheels to the right by adjusting the tie-rods.
Here's your process - paint mark the relative location of the male/female threads on your tie rod ends. Loosen the jam nut (hold the outer tie rod with a wrench) on the driver's side, then screw the male threaded rod into the female (this is for our example where steering is off in clockwise direction). Do exactly half a turn, or a whole turn, but count and be exact. You've just rotated the left front wheel in by a few fractions of a degree. Tighten the jam nut. Now on the passenger's wheel, do the same procedure, but unscrew the male thread from the female by the same number of turns. This rotates the passenger wheel out. Tighten your jam nuts and test drive.
Unless you have some strange tire wear that makes you think your total toe is a problem, as long as you change both tie rods by the same amount in opposite directions, you don't affect total toe - only clear vision. The Expedition we bought last year had a clear vision issue. The 1/2hr it took me to fix it was less painful than the hassle of taking it to the dealer. I did a full turn at first and it was too much, so I backed off to a half and it's now spot on.
