Use the function RegisterUserEditor to register a resource type editor.

typedef void (*EditorCreateFunc)(Widget, ArgList

Cardinal, XtPointer);
typedef void (*EditorUpdateFunc)(char *, XtPointer,

Widget, XtPointer,
XtPointer);
typedef void (*EditorFetchFunc)(Widget, XtPointer);

void RegisterResourceEditor(char *resource_type,

EditorCreateFunc ext_create,
EditorUpdateFunc ext_update,
EditorGetFunc ext_fetch,
EditorCreateFunc simple_create,
EditorUpdateFunc simple_update,
EditorGetFunc simple_fetch)