I will assume that you have a field named __pkCustomerID that identifies each customer uniquely in your Customers table and that you are Using FileMaker 12 and that, if you are using windows, your windows are NOT maximized:
#Open Customer List Window
New Window [ //specify name, position and size of the window here. Use advanced window options to make it a modal window]
Go to Layout ["Customer List" (Customers) ]
Show/Hide Toolbars [Hide]
Show All Records
Sort Records [Restore ;no dialog]
Script 2: (perform from button on Customer List layout)
Set Variable [$CustID ; value: Customers::__pkCustomerID ]
Close WIndow [Current Window ]
Enter Find Mode  ---> clear the pause check box
Set Field [Customers::__pkCustomerID ; $CustID ]
Perform FInd 
If you want, you can select the name fields on the Customer List Layout and use Button Setup... to turn them into a button to perform Script 2 when clicked.
For more examples of scripted finds that use this format, see: Scripted Find Examples
If you are using Windows with maximized windows, let me know and I'll describe how to minimize an annoying issue with what happens when you open a new window when windows are maximized.