You will have to investigate what ports (at layer 4) are used by these p2p apps. Once known, you can define a min and max bandwidth for one of the 8 available hardware queues and then define an access list to put all traffic using these ports into this queue. Extreme calls this act creating an access profile. Lets choose qp4 (qp1-qp8 are available, everything is in qp1 by default) for example.
configure qp4 minbw 0% maxbw 30% priority low
(low just means the 802.1q bit is set the same as qp1, you would want that on tagged links. also, don't mess with the minbuf and maxbuf settings)
This restricts the max port bandwidth to 30%, use whatever you want here. This will probable be fine on only the switch connected to the internet feed but if you think a problem with p2p internally is happening, you need to put this on all switches. Tagging negates this need but that is a whole other topic.
Next, on the switch that routes to the internet:
create access-list p2p tcp destination any ip-port range 3000 4000 source any ip-port range 3000 4000 permit qosprofile qp4 ports any
I am guessing that kazaa uses tcp but if its udp, adjust accordingly. the port range is a guess to show the command syntax. I think you had all i series equipment so this is all good, non i series is a bit different.