I just did the same thing today, and I already had him in another league at first. Here are some things to know, and why people should jump on this guy:
1) Yes, he has 7 games at 3B, and needs 8 more in the Yahoo league, and he will get.
2) He will play 3B when (it is when) Damian Easley gets hurt again or is slumping badly. Easley was out for a week, but since Travis Lee was also hurt, they needed Huff to play 1B, so he was already THAT close to have 3B eligibility. Next time Easley is out, it's all Huff.
3) When interleague play starts, if Easley is slumping, they'll most likely bench him and play Huff b/c they'll want him in the lineup (no DH), and they want the bats of Lee, Baldelli, Crawford and Grieve (OF) more than Easley.
So my prediction is that by All-star break, hopefully before, Huff will be 3B eligible, making his value skyrocket , because right now if he's 3B eligible, he's a top 5 fantasy 3B, which is right where he'll be in my lineup.
If you have a roster spot, get him while you can, even if you have a solid 1B and 3B situation, because he'll have tremendous trade value in a month or so.