You can tie into the tractor hydraulics, but there are two things you will have to do. First is to install a power beyond setup, which is fairly simple. That just involves hooking some hoses into some of the ports you mentioned earlier.

 The other thing is you'll need to buy a flow divider so that you aren't sending all of your hydraulic pressure and flow through the steering system. You can find flow dividers from places like Northern Tool.

When it comes down to it, you might be just as far ahead to find a small power steering pump of a junk car, and find a way to mount it on the front of the engine. Either way will work, let us know what you want to do and we'll do our best to help you out.