dim proca as *Function() As HWND
dim hwnd As HWND

proca = GetProcAddress( GetModuleHandle( "user32.dll" ), "GetDesktopWindow" )
hwnd = proca()
Print Hex$(hwnd)

こんなんでおｋ
引数があるなら
dim proca as *Function(a As Long,b As Long,c As Long...) As HWND

関数ポインタの戻り値を直にPrintすると怒られるんだが
これの理由はよくわかんね