The ISO 2631 Whole-Body vibration filters Wk (vertical) and Wd (horizontal) can be applied by right clicking on the Y-axis of the vibration spectrum display.
Right click and choose "Processing -> Weighting/More -> Wk or Wd".
This is possible from Testlab Revision 18 and higher.
If wanting to filter time domain data, under "Tools -> Add-ins" turn on "Human Body Vibration".
In the Time Signal Calculator, a new function called FILTER_ISO2631 is added to the list of available functions.
It can be used to filter time histories.