Once you know how, it's not too hard to set up a forestry autofarm two different ways. The first is to craft an intricate circuit board, craft a soldering iron, get four of the right kind of electron tube (I forget which one you need for rubber farms but the wiki knows), right click with the soldering iron and put the circuit board along with the electron tubes in. Then, put the circuit board into the multifarm. The second way is to make it a regular tree farm and then send the wood into an extractor. I think this is the easiest way if you have enough saplings to make it sustainable.
That or the already mentioned MFR farm.