Path - This is where you'd place the path to the exe that your adapter is launching.
TargetPath - This is only used if the application in the Path launches another application and you wish to hook only that application (and potentially its children). This is only used with the StartMethod of StartAndWait.
Arguments - This is where you'd include any command line arguments required to launch the application specified in the Path property. Basically, anything on the command line after the exe.
In your example, it appears you have an odd command line in that arguments come first. I don't believe that is valid. Are you able to paste that into a command window and launch the application from there? You can use a tool like Process Explorer to help determine the arguments used when an application is launched. I would suggest that you examine the application with Process Explorer to determine how it is launched.
Aside from the first part of your command line (Target: ("P1" "P2" P3)), it looks pretty straight-forward. I'll leave that off as I believe that is either a typo or I am missing something that would require some hands on.