I find it a lot easier to use moleskin than a special foot. As someone else mentioned, moleskin is available in the foot section of pharmacies. I use my rotary cutter to cut strips of it to have on hand.
To position the moleskin, I use my favorite ruler (you can also use 4-to-the-inch graph paper) and lower the needle so it touches a little to the right of the 1/4" mark. I make sure the ruler is positioned straight from front to back (I often place another ruler next to the one I am using and position the straight lines on the ruler in relation to the needle plate markings), then lower the presser foot to hold it in place. I remove the backing paper from a strip of moleskin and position it so it butts right up against the edge of my ruler. I like the moleskin to run as far as possible to both the front and back of the ruler; helps me keep the fabric feeding evenly.
I find with this physical barrier that I can sew long strips together much faster than by using my eyes alone, plus it is easier and more accurate.