TR.P 0 safely does nothing, which you can use to your advantage here. Sadly the line would be too long to fit, so you need to break it up:
Q LT RAND 100 57
DEL DIV LAST 1 2: TR.P Q
If you used a normal variable instead of the queue, any other script changing it during the delay can cause the wrong channel to trigger. Of course if any other script messes with the queue this will break too. 
If you wanted 50% rather than 57%, you could use:
DEL DIV LAST 1 2: TR.P TOSS
Another two-line solution:
PROB 43: BREAK
DEL DIV LAST 1 2: TR.P 1