"The default ⌃H behavior comes from the Standard Key Bindings file in the AppKit framework resources. You can override this easily.
Create a file with this as the contents:
{ ""^h"" = """"; }
And save it to ~/Library/KeyBindings/DefaultKeyBinding.dict, creating the KeyBindings folder if it doesn't exist. (Note: you will need to restart your applications for this to start working.)
(Another side note: I'm not entirely sure if using """" is the right way to make it do nothing, but it works. The documentation I found said nothing about any no-op methods.)"
If DoubleCommand isn't working for you you could try creating your own keyboard layout using something like Ukelele. I've never done it though, so i'm not sure how much work it is.
