Well you could just cut to the chase, and create the timer (over and over), when you type.

[color:orange]; Triggers when you type something into '#help'

On *:Input:#help:{
; Checks if its a /command, if not proceed.
if (/* !iswm $$1) {
; creates a timer (if exists, resets) to part '#help'
.timer#help 1 420 part #help
; end if statement
}
; end event.
}
[/color]

Edit:

[color:orange]; starts timer when you join.

on me:*:JOIN:#help:{ .timer#help 1 420 part #help }
; stops timer when you part
on me:*:PART:#help:{ .timer#help off }
[/color]
Eamonn.