Thinkorswim allows 19 custom quotes for use as customized columns. They can be used on the Trade tab, Stock Hacker Scans, and Market Watch Quotes.
In order to use the Custom Quotes you must first be on one of the screens that support them. Right-click on any column heading and select Customize.
Type 'custom' in the search box that says 'Lookup a column...' This will filter out all but your custom columns, even ones that you rename.
Click the scroll icon for the custom column you want to edit. Click on the thinkScript Editor tab and delete any code that exists. Copy the desired code and paste it on line 1. Fill in the Column name to match.
After customizing each column they must be added to the current display set. You'll probably have to remove some of the existing columns to make room. Make sure that you save the Workspace so that your customizations are easily recalled.