Try a drawknife. It is what I use. You can find them at flea markets, antique stores, or at worst, in woodcarving catalogs.
It is best to get your hands on freshly fallen wood, as, in my experience, the greener the wood, the easier the bark is to remove. I have never dealt with Beech or Elm, as I live way down south, but Oak is certainly easier to work with green, and Hickory is even better.
If you are stuck with nothing but deadfall and a regular knife, use small, precision cuts (no more than an inch long apiece) to remove the bark. I know it is tedious, but the results will be better.
Oh yhea,as an aside, if you get a chance to use green wood, strip the bark off ASAP, and dip the end grains in wax. then put the piece up for one year per inch of thickness in a dry place. This will keep the wood from cracking by allowing the moisture to escape from the sides slowly.
Just some suggestions.
"...Let there always be inequity in defense. Always protect thrice as fiercely as one is attacked"
From the Nine Noble Virtues