I've never played a Plus League on Yahoo, but I know that you can't in regular old free Yahoo.
A site that you can change position eligibilty, although it doesn't offer baseball yet, is [url]sports.ws[/url].
I'm in a basketball league there, and it's free, and you can have the league vote on position eligibility, how much power the commish has, etc. And it's divisional. It's also a totally different kind of fantasy league. You get 48 minutes for your centers, 96 minutes for guards, and 96 minutes for forwards. This way guys who play less minutes are still worth something because, for example, you can platoon 3 C's who play an avearge of 16 minutes each, and still be competitive with a team who has 2 C's playing 30 minutes each.
There's way too much to explain about it, so if you're interested go check it out. They have football, basketball, hockey, soccer, etc....everything except baseball (probably would be too much traffic, they rely on donations and it's not a large company with tons of sponsorships). I hope they do a baseball league for the upcoming season
but if not, at least Yahoo is still free.....for now. Did I just jinx it......