I don't think there is a cluster of EU boxers. For the very simple reason that if someone is still in a boxing guild, they're probably enjoying wow and not SWTOR. If they're not in a boxing guild, then they probably created toons where their friends did.
Besides that boxing wow or boxing SWTOR atm are 2 very different things. Wow is ez compared to SWTOR from what I can tell so far without actually boxing myself. So I think there will be a lot less boxers in SWTOR to begin with.