Once you develop your custom code and develop your build you will have to open "swfconfig.xml" file in local machine under QTP installation path where you will have to copy and paste the xml stub generated post building your solution in VS. Once this is done go to extensibility folder in qtp installation path and open .net folder and open TestObjectConfiguration.xml file and you can define your Object model with "SwfEditSpecial" object type. Hope this helps.
Note: Extensibillity defers from technology to technology and according to project you may need to do some additional things in order to make it work.
I am using QTP11.0
I do not find the file "TestObjectConfiguration.xml" however I have this file in the extensibility folder:
"C:\Program Files (x86)\HP\QuickTest Professional\dat\Extensibility\DotNet\DotNetCustom ServerMethods.xml" is it the same?
Using this file with this format, I was able to map my own functions, but it still recognizes it as "SwfEdit". When I changed the BaseClassInfoName to SwfEditSpecial it only removed the base methods of SwfEdit, but still recognizes it as SwfEdit.