I have been doing some object coding recently, and yes you can hard code references. It is as simple as replacing the attr_ code with a constant or variable.
Eg. from something I am working on:
MidiSend3((midi_device_t) MIDI_DEVICE_DIN, 1, MIDI_CONTROL_CHANGE +
This code is based on the midi cc out object. I have replaced the attribute 'device' with 'MIDI_DEVICE_DIN' which was in a spinner. It lives in a function in the local data tab.
Params can also be hard coded in local data. Hope that is what you wanted to know.