[CentOS] On SSH

Hello,

does anybody know how to achieve the following with SSH...

    a) accept RSA authentication for all but root from any IP
    b) accept RSA authentication for root from a couple IPs/Netmasks
    c) accept password authentication for all but root from a dozen Netmasks
    d) accept password authentication for root from 3 local netmasks only

ie. make authentication depend on the USER,METHOD,CLIENT-IP triplet...

Cheers,
MaZe.