Register for one of the CHAT_MSG events
here.
Then arg1 will be that chat line in your mod.
function MyMod_OnLoad()
this:RegisterEvent("CHAT_MSG_COMBAT_SELF_HITS")
end
function MyMod_OnEvent(event)
if event=="CHAT_MSG_COMBAT_SELF_HITS" thenDEFAULT_CHAT_FRAME:AddMessage("_COMBAT_SELF_HITS arg1 is "..arg1)
end
end