You would just need to build a new import library for the SDK (easier than it sounds) and go from there.
You would just need to do that if the DarkSDK was a dll, but it is a set of .lib files which only work for VC++. They planned to release a Dev-C++ (this is, GCC based) version, but I don't know if that will ever be done.The only option to use DarkSDK right now on BlitzMax would be to create a .dll with all the .lib files, and the import the dll into BlitzMax. The problem is that I don't know if DarkSDK allows the distribution of the functions inside a Dll. AFAIK, you must statically link it into the EXE.