There's no way that the Gateway, or any other keyboard for that matter, does any of these fancy features "in hardware." That' just not what hardware does. In fact, most hardware doesn't do much of anything without software.
And it's the software, whether it be an application, control panel, userland driver or some other patch into the OS, that does the fancy remaps and macros.
It does sound to me that any of the fixed-function macros can easily be done with Girder, but personally I can't stand its interface. If you thought it was hard to do anything in the tools you've already tried, then you haven't seen the mess that is Girder.
However, there are other tools available. One such tool is uICE frm MediaTexx, which among other things, supports profiling remote control devices and natively also supports keyboards. You can create any number of crazy macros or anything else for any key or combination of keys as far as I remember. It gets better, because you can have all your settings saved as application-specific profiles. So if you really needed a different set for a specific application, no problem.
The program is always resident (you'd have it start with Windows), but I don't know if it has any configuration that is "on the fly" without input into its control panel-like interface. HOWEVER.... The author is very receptive to good functional ideas, so this is something that can alwas be requested. I asked for something even before registering the program and he added it into the very next version - which was out the week after I sent the email.
And even if that dosn't work for you, I am sure there must be another program out there to allow fr on the fly editing of at least a single key for repetitive tasks. You can't be the only person who likes the feature of the product you're now using, right?
Of course, what you're describing also sounds like it would be a feature found in whatever editing application you're using to manage these contracts. I know my text editor supports all sorts of key-assignment features and macros. Plus really great search and replace that can handle dozens of documents all at the same time. YMMV of course.
Just an FYI.
http://www.mediatexx.com if you want to check out uICE.
Bruno