I can't really see this working. We have, what, 6 customizable windows that chat channels can appear on? And each window could be further divided into any number of custom tabs. A slash command would need to take parameters for what window and tab to add the channel to, and you'd have no way to ensure that every player gets the channel added to the right window for them. If it only took the one parameter like "/addchannel request", it would probably only get added to whatever chat tab is currently active for the player's client, another thing you'd have no way of predicting. In short, there's no way to idiot-proof this.