I'm changing mine, but I have the transmission taken apart. I wouldn't think it would be hard to change it together though. Just take your Pivot Arm/Throwout bearing off, then there is 3 or 4 small bolts that hold the slide for the throwout bearing. Take that off, dig out the seal and replace with new. Just be careful not to damage the shaft or housing. I've got the specs on the seal at the house and can get them if you need it.
BTW.... Ford wanted $25 for the seal. I took the measurements to my local bearing shop and got one for $4.