The mentioned link actually states the following:
consider implementing the count-down functionality (as a modification) to ensure that the user is informed (e.g. gets a popup) about upcoming timeout event.
And there is an attachment at the bottom as:
Code Modification Sample
Attachment: AboxExecution.pdf
Check this file in order to get the code from IC_BASE application ABoxExecution view.
Also IC_BASE can be found not in tx. BSP_WD_CMPWB but in ABAP Workbench. Go to se80 then choose "BSP Application" from the dropdown and put IC_BASE as a name. You'll find the view in "Views" folder.
And here is the actually quite informative blog how to achieve your requirement SAP CRM: Webclient UI - Framework: Session Time... | SCN.
Written by Nitin Gupta