How to associate a file extension to a program without making it the default program

Question

I\'m deploying a small conversion tool on some systems, and want the users to be able to run it from the right click Open with menu. But I don\'t want to change

Answer 1

Setting the following keys worked for me:

key HKLM/SOFTWARE/Microsoft/Windows/CurrentVersion/App Paths/: "" = 

key HKCR/Applications//SupportedTypes:  = ""
key HKCR/: "" = 

key HKCR//OpenWithList/
key HKCR//OpenWithList/
key HKCR/SystemFileAssociations//OpenWithList/

delete key and subkey at HKCU/SOFTWARE/Microsoft/Windows/CurrentVersion/Explorer/fileExts/