Here is one right from the horse's mouth:
http://www.absorbine.com/products/hoofcare/hooflex-liquid-conditioner
http://www.americanlivestock.com/p-652-hooflex-cond-liquid.aspx
About a decade ago a was looking for a cheap tire softner-traction aid for some well used MC Creary Road Start circle track tires, that were getting used as rear street slicks for fun. I kept searching for products with Rosin, which was used a long time ago for traction at drag strips. The ingredients: Petroleum, Neatsfoot oil, Lanolin, Turpentine, Pine Tar, and Rosin - clean, soften, treat, and give some stick. The bottle is about 10-12 bucks. The lid has a built in attached brush. I found by brushing it on the tread with good coverage - then use a heat gun to help the tire soak it in - the sit overnight - worked the best. Give a good wipe down or burn out to clean them off, and PRESTO!
Formula V works well. And that gallon goes a long way. After using the Aborbine the night before - the nest day spray on the Formula V right at the track with a spray bottle on the tires.