I would start a facebook page with your farm name and work at getting some people to "Like" your page, its free and really east to do. Depending on how serious you are about it and how much something like that would go for, I would contact some of the jackpots that are coming up in that area, get ahold of someone who is putting it on and email them a flyer that you have put together. Keep it short and sweet, but don't single yourself out to just one steer.
Make some calls. Go to showsteers.com and look up your target state whether it be Texas, Kansas, Oklahoma. Search through the sites listed for either hereford breeders or steer jocks. Most people in this business love to talk about their animals. Ask them what they have, let them talk about it awhile, and work into the conversation what you have and see if they, or know of someone who, might be interested in something like what you have. I guarentee you that if you put the leg work in, you will be rewarded.
Whats interesting to me about what you are offering is that its unique. Just as was pointed out before a very small percentage of people do what you do, but in my opinion, that just means your opportunity for growth is huge. You have a product that noone knows they want (need), until you show them. I'm sure there are a lot of folks out there that would love to get there kids showing a year or 2 earlier, and their kids want to, but they don't want to risk it with a 1200 lb beast. You have the perfect solution, and because of that, you can get a premium for it.
Good luck and be sure to let us know how it goes!