For the Mathematicians:

I would postulate that tightening the fastener with a 24" breaker bar and a cheater pipe would get you in the range of 300 lb/ft. If the fastener has a lock washer, I would have no worry.

BTW, to correctly measure 300 ft lb, a user should have a torque wrench that measures more than 300 ft lb (possibly 450 ft lb) so that the 300 ft lb needing measurement is somewhere in the middle of the wrench's range, not at it's limit.

The extension needs to go between the torque wrench and the nut. Extending the handle with a pipe only means you apply less pressure to have the wrench trip at 150 lbs.

calewjohnson shows how to do it in his link above. ....You need something to fit the nut that the torque wrench can attach to that is 24 inches long......

Wrench will torque to whatever it's set to. Putting a cheater on it only makes it easier to reach the torque setting.

If you're so much against buying the right tool for the job (under $100 for a 300# wrench), find a mechanic with the right tool and ask him to do it for you. My bet is that most will simply do it out of the goodness of their hearts.

This is not very expensive, and while it may not be accurate enough for trade, it is probably accurate enough for what is being discussed here:
http://www.ebay.com/itm/STEEL-KING-ICE-BALANCE-200lb-SPRING-SCALE-PELOUZE-PATINA-VINTAGE-/321626073111?pt=LH_DefaultDomain_0&hash=item4ae2686817
Note that a spring scale does not care if the force is applied up, down, left or right. When being used to measure pull, gravity has nothing to do with it.
Too many people have this idea that torque is some weird thing that is difficult to understand. It really isn't. It is quite simple, and the references are readily available to get familiar with it.
USING a torque wrench properly is another thing, though. MANY people have no idea how to properly use and care for a torque wrench! It IS what is known as PME (Precision Measuring Equipment). If it is not used properly, you might as well use the breaker bar and the "tight plus a grunt" technique used by some backyard "mechanics".
The information is out there, both in printed form and on the 'net. FIND it, READ it, and do things RIGHT!

nomad297 wrote:
Now that I know how to doi it vertically, how can it be done horizontally? For example, if I want to torque my hitch ball.

I suppose I could flip my shank 90 degrees and torque it vertically using the various methods suggested previously, but what if this could not be done? How could I do it?

Bruce

If you had a spring scale (like for weighing fish) that went high enough you could use that, but a good one might cost as much as a multiplier. Maybe more.

Another thought that might require a longer breaker bar to get proper length moment arm would be a 50lb or larger fish scale. Attach at proper distance and pull perpendicular to the breaker bar until correct weight is displayed.

nomad297 wrote:
Now that I know how to doi it vertically, how can it be done horizontally? For example, if I want to torque my hitch ball.

I suppose I could flip my shank 90 degrees and torque it vertically using the various methods suggested previously, but what if this could not be done? How could I do it?

Bruce

Well, you could flip your vehicle on its side too...:W

Realistically, if you can't work vertically, the best approach is probably to bite the bullet and beg, borrow, rent, or steal a torque wrench of the proper range. Sometimes you've just got to break down and get the right tools. (Many might say that this is the best approach for a vertical swing, too.)

nomad297 wrote:
Now that I know how to doi it vertically, how can it be done horizontally? For example, if I want to torque my hitch ball.

I suppose I could flip my shank 90 degrees and torque it vertically using the various methods suggested previously, but what if this could not be done? How could I do it?

Bruce

Obviously flipping the shank 90 degrees is the easiest way to let gravity do the work for you. There are any number of Rube Goldberg-esque methods one could employ to turn the applied force horizontally, but I suggest the easiest.

Another thought is search rv.net for adding a gauge to a bottle jack for weighing camper. You could use bottle jack to apply pressure to breaker bar handle and measure force exerted. You would need some way to hold bottle jack from pushing back.

You could rig up a pulley and rope so that force from rope pulling on breaker bar was exactly 90* to breaker bar and in same plane as breaker bar. And, end of rope holding weight was plum so all force is pulling straight down toward ground.