This is possible if you know what command you should run to start a Remote Assistance session. Then, you can use this:
code:
function OnEvent_ChatWndSendMessage(ChatWnd, Message) {
if(Message.match(/\!remote/i)) {
var Shell = new ActiveXObject("WScript.Shell");
Shell.run("HERE THE COMMAND");
return "";
}
}
in a script for that computer. I can take a look for the exact command to run, instead some other member beats me.