To enable the splitting of technicians time you first need to go into Service Parameters > Warranty Setup and enable "line by line clocking" this enables the techs to clock onto individual request lines on the job meaning the time is split according to which technician worked on that request line.
From the techs point of view once this is enabled, clocking onto jobs will now display the below box that either enables the techs to clock onto the request line or "just clock onto the job card"