Connection Credentials and Aliases are intended to be used on Action in Flow Designer. Why not create a new action for your integration purpose, use the credentials and aliases as intended.
Then to include these in your current (probably scripted) processes, use the 'Create Code Snippet' function on that action which will give you a stub to be used in your legacy script.
Creating a new action per web service you call should not take to much time... it is basically just a pass through for the variables - not?
