I would first set updown messages to go to a specific file on the box like this:
[edit system syslog]
file interface-logs {
any any;
match UpDown;
}
Then if you want to see them on the console, you could type "monitor start interface-logs" to start seeing the messages in that file as they occur on the console. The command "monitor stop interface-logs" would turn off the console logging for that file. I think that would take care of it.
Ron