I just recently used the following clause to find stocks with the narrowest Bollinger Band width in the last 130 trading days. It seemed to work. Change the 130 to whatever number of days you prefer.
[BB Width(20,2)<= Min(130, bb width(20,2))]

 Anyone know how to scan stocks that have -DI readings of less than 10 or greater than 50?
[daily minus di(14) > 50] or [daily minus di(14) < 10]

I'm trying to create a scan that has the green ADX above15 and the red ADX below 20. I'm trying to find stock just before the green and red cross as a bullish indicator.
[daily plus di(14) > 15] and [daily minus di(14) < 20]
and [daily minus di(14) > daily plus di(14)]
and [yesterday's daily plus di(14) < daily plus di(14)]
and [yesterday's daily minus di(14) > daily minus di(14)]

The AUI says that Syntax is correct.
I haven't run the scan to see if it works.

In that scan, I asked for
+DI more than 15
-DI less than 20
+DI rising
-DI falling
-DI above +DI

There are many ways you might approach what you want to do using the Standard Scan Engine.

For example, using the Multiplier, you could have
-DI above the +DI by at least 10% yesterday
and
-DI above the +DI by less than 10% today.

You could pick any % you wanted.