OOB Pick Ribbon Button Custom Alert in Queue Item

Hello All , 

I have a Requirement to create Custom pop up Alert using OOB pick button in Dynamic 365 .

When a user select a Queue item and hit the pick button so we already have OOB pop Up alert stating this item assigned to specific User .  But I need to create new alert after this OOB pop up alert with Customised text . I have tried with Ribbon workbench but not sure what needs to done to have new custom alert .Any help will be appreciated . Please find the attached screenshots .

Note : I have to add new custom alert after the OOB alert on hitting the Pick button as highlighted in red . 

Thanks