Load it onto any weekly chart. The data displayed is independent of the chart instrument.
On the Inputs tab, uncheck "Show Legend" to hide the legend (useful if you want to change the plot colours or it is getting in the way).
On the Inputs tab, select "Total OI" to show the net positions expressed as a percentage of Total Open Interest; or "Non-com positions" to show them expressed as a percentage of Non-commercial Longs + Shorts. The default is "Total OI".
On the Style tab, change the plot colours, etc. as necessary. Note that the legend will not reflect the new colours.
This is my first script and I couldn't get some things working as I wanted (such as multi-line declared functions and if-then-else blocks), so sorry the code's a bit clunky. Please feel free to copy and modify it however you wish.
An FX version is also available.