The "dummy DLLs" are created from scratch, and do not use or require any piece of the original file. If what you're after is to create dummy files similar to the CD_CLINT.DLL dummy, you need to find out the functions the original DLL exports, how each one is called (e.g. what kind of data, and how much of it, the host program passes to the real DLL), and the proper return value that will keep that host program happy. There is typically an SDK available to adware developers using a particular DLL, if you can get ahold of this, it will tell everything you need to know.
A fictional program, HuZzAh, uses a fictional ad/spyware DLL, adfeces.dll. When HuZzAh starts up, it calls a DLL function such as StartAdBlasting(int height, int width). In the real DLL, this function connects to the internet and downloads ads, and returns "1" if the downloading was successful, and "0" if it was not. If HuZzAh receives the "0" response, it complains loudly and refuses to run.
When creating your dummy file, just create a DLL in any programming language that lets you, and create empty functions named after all the required exports. These empty functions do nothing except accept the data passed to them, then blindly return whatever data is necessary to keep the host program happy. In C++ Builder, this looks something like:
int __stdcall StartAdBlasting(int, int)
If what you are trying to do is simply hand-edit an EXE or DLL to e.g. change the phone-home URL to localhost, set the banner size to 0, etc., you can use any old hex editor or even Wordpad. You can also use a free program called Resource Hacker
to do this more easily.