If I'm understanding correctly, you want to send the same message to all channels that you're in. If so, then use /amsg <text> or /ame <action>. This is limited to just the active network, but if you want it in all networks and on all channels, then use /scon -at1 amsg <text> or /scon -at1 ame <action>
For more details refer to /help /amsg
If I'm wrong, then please try to clarify.