Starting external file in web client

Starting external file in web client

My external file (file used in ActiveX control container) is coppied as other files to C:\users\Administrator\...\zenWebCli ... folder. obviously I can not give full path to 'Start program' function because it includes user name that is different on each computer. 
I've tried using %LOCALAPPDATA%\Temp\zenWebCli ... as path to my file but it seams Zenon web client can not use such path name. 
Is there a way to reference such folder path in 'Start program' function ? 

Thank you and best regards to all