...does this help?
Adding "Open With" Menu Command
The Open With context menu is only available when you Shift+right-click a file. But there is a way to add this option automatically to the menu every time you right-click a file. Launch the registry editor and go to HKEY_CLASSES_ROOT\Unknown\shell\openas\command\
. This subkey is actually the action to open the "Open With" box for "unknown" files when windows can't find the suitable application to open a file with.
To add this action to every file, we must copy out the value of the Default
string on the right pane. Press Ctrl+C or right-click and select Copy.
Now go back to the top of the list and HKEY_CLASSES_ROOT\*
. Right-click on it and choose New Key. Name this subkey shell
. Right-click on shell
key and add a new subkey named openas
. Right-click this key and add a new subkey named command
. Now double-click the default
string value in the right-hand pane. A dialog box will pop up. Press Ctrl-V to paste the complicated command line you copied earlier. Click OK.