<enlightened..
Les..... simple answer is that tool wise, Alf got it right on the money.. though you'll need a good straight edge, a square and something to act as a pair of winding sticks too...
to tackle it... clamp each stick with its flattest face down... and work on the opposite face. To begin with, concentrate on getting that face flat along its length and make sure that it's twist free (hence the winding sticks)...
With one good face, rotate the stick through 90 deg and repeat the process, adding an additional check in that the 2nd face must be square to the first throughout its length...
For best results, it's gonna pay you to take your time, be fussy in getting each face as close to bang on as you can... With 2 good faces that are square to each other, you have a decision to make (provided you have access to the tools)... whether to carry on working by hand, or to mill your stock to a fraction over finished side with a thicknesser... always leave a little material so that you can plane the machined faces to final size...
I won't try to persuade you one way or the other, other than to say that if you choose to machine the last 2 faces, you should allow an additional 4-6" of length to allow for snipe in the faces... if you choose to complete the job using handraulics, you can ignore that...
Completing the job by hand is a simple extension of what you've done so far, working on the next face in sequence, getting it flat, true and twist free while being square to the previous face. The additional step here is that you need to keep planing till you hit your desired thickness...
The only thing you need to mind is that you hone the blade as soon as you feel that the plane's struggling a little.. Other than that.... it's a fine easy job... if a little time consuming...
btw.... what kinda stock are you using...??