Ok just looked at the source a bit. Here is what I have found out so far.
There is a missing file or old file still listed in the mame tree called ladyfrog.c. To get rid of the compile error you can just delete it, make an empty file called ladyfrog.c, or go to the file right click select settings and exclude it from the compile (under the general tab).
The xbox_Main.c has a problem. You'll see 2 lines:
// g_font.Create( pD3DDevice, "Font.xpr" );
g_font.Create( "Font.xpr", 0 );
Change it to:
g_font.Create( pD3DDevice, "Font.xpr" );
// g_font.Create( "Font.xpr", 0 );
Probably has something to do with the XDK. Cause the g_font.Create requires a D3DDevice pointer according to the error message I received.
Forget about the stuff about konamigx.c, it caused a few more compile errors so I removed it again.