I used to have a small amount of a junk bond fund. If you're going to hold it, your IRA is the place because of the tax treatment of the distributions.
That said, I dumped mine. There's no real point to it I figure, junk bonds returns are highly correlated to stocks...but return less. So, better to just own the stocks I figure. On the other hand, if you're looking for safety then a typical bond fund is more appropriate than junk bonds, since there's no safety to be had in them (well, no safety from stock market downturns that is). If you're going to own junk bonds, I'd consider it part of your stock allocation.