How do I encrypt app.config file sections during install with WiX?

[admin]

I have found an example for encrypting a web.config during installation <a href="http://madtechnology.wordpress.com/2007/05/04/using-wix-to-secure-a-connection-string/" rel="nofollow noreferrer">here</a>, but my app is a windows service. The

aspnetreg_iis

method works only for web.config files.

I know how to programatically encrypt the config file, but I don't think I can do that using WiX. Am I wrong? Any ideas?