I just did this today. Had the chirping/squeaking sound for about a month now - sometimes quite loud, other times it goes away after warming up.
It was more work than I expected since you have to remove a fair amount of stuff to gain access to the synchronizer. I wound up taking out the air cleaner housing and throttle body for better access to the general area. The real obstruction was the cable harness that passes directly over the cam sensor. I had to open up the plastic cable cover, disconnect the heater hose that goes to the top of the cylinder head (about 1/2 cup of antifreeze spilled out) and push up the lower part of the plastic cover to have clearance to get to the boltheads holding the sensor to the synchronizer and the big bolt and washer that secure the synchronizer in place.
I did not use the special tool. Instead, I use the guidance of another clubber (see topic 10883) and used a sharpie to mark the relative location of the little tab that moves inside the synchronizer to the outer edge. I placed a mark on each edge of the tab so there were two marks with the tab in the middle.
Then I marked the location of the middle of the small notch (that is diametrically opposite the big notch where the sensor connector rests), on the cylinder head. I removed the old synchronizer, marked the new one with the tab locator markings and then installed it.
See the attached photo for clarification.
It took a couple of tries to get the helical gear in place so that all the marks and tab lined up. If you are off, it is obvious as the tab will be outside of the two marks you make.
If you do this, make sure you clean off the surfaces that you will be marking with the sharpie with some kind of solvent. You don't want the marks rubbing off! I used brake cleaner.
The old part definitely was the cause of the squeak even though it looked fine from the outside. I just turned the parts in my hands and it squeaked. My guess is that the bearing surface gets starved for oil as it wears; after oil pressure builds up, it gets enough oil to quiet down. However, it probably will continue to degrade and get noisier.
The engine fired right up after I put everything back together. I cleaned the throttle body while I had it off as it had quite a build-up of gunk on the surfaces.
Few more things for clarification:
This is a 2001 Taurus SES with Vulcan engine.
The part is DA-2089 from the Ford dealer - cost me $135 including tax.
I did not have to mess around with getting cylinder 1 to TDC as you just need to preserve the relative orientation of the synchronizer body to the cylinder head, and the rotating inner tab to the synchronizer body.
I reused the sensor since it looked fine - saved $35. I did not have any ODBII code or check engine light.
Also make sure you wet down the helical gear with motor oil before you mount it in the engine.
Thanks to all the earlier posters for sharing the info!