that is kinda what i want, but i think its a tad bit more complex than that :S
you have objects in your scene, and you pick and object, go to the channel box and thats where you set keys normally right?
well for this, i want it so, you run the mel script and a window pops up, you select an object and that mel script windows *automatically* refeshes and it shows a list of that particular object's channels (like you said above with ur lovely diagram) but these channels in the script window wouldnt just be translate scale and rotate, it would include custom attributes as well (id say this is the most important part).
the last thing is, instead of having checkboxes, id like to have each attribute (eg. rotate y) onto a clickable box, and when that box is clicked, that one attribute is keyed, so you can just click names and keys would be set for the names you clicked (simpler than checkboxes
and then you deselect the object and the mel script window shows nothing inside it, you select another object and the mel script window would refresh showing all the channels/attributes of that new object
so its all about automation really
sorry if im being so totalyl awkward, cos i no i am