[Phanx]

Something like this should work:

local function apply(editBox)
	editBox:SetAttribute("chatType", "GUILD")
	editBox:SetAttribute("stickyType", "GUILD")
end

-- apply change to all existing chat frames
for i = 1, 10 do
	local editBox = _G["ChatFrame"..i.."EditBox"]
	if editBox then
		apply(editBox)
	end
end

-- apply change to all future chat frames when they are created
hooksecurefunc(ChatEdit_OnLoad, apply)