Are you after one of these, e.g. rotate?

    >>> C.window_manager.keyconfigs.user.keymaps['Transform Modal Map'].keymap_items[5].propvalue
    'ROTATE'

I'm pretty sure there's only one modal map for all transform operators (and not changable with python).

    import bpy
    wm = bpy.context.window_manager
    keymap = [k for k in wm.keyconfigs.user.keymaps['Transform Modal Map'].keymap_items if k.type == 'G'] #k.propvalue=="TRANSLATE"]
    modal_translate = keymap[0] if len(keymap) > 0 else None
    print("\n", modal_translate)
    for attr in dir(modal_translate):
        if not attr.startswith("_"):
            val = getattr(modal_translate, attr)
            if type(val) in {int, float, str, bool}:
                print("\t", attr, "=", val)

But note that you can't provide an operator name in modal maps. Only the predefined modal operations can be set (`propvalue`).