That's right-you can't make an ADR for the bar itself, but when you arrive you could just ask to be seated at the bar..if there is room.
We ate at the bar there in early October. What we did was make the regular ADR. When we arrived we checked in on the 2nd floor, went up to the restaurant and with pager in hand (there was a 40 minutes wait) went to the bar. We miraculously found 2 open seats, sat down, then asked the bartender if we could eat there. "Sure thing" he replied, took our pagers and gave them back to the hostess. Whereupon we had a wonderful meal!!
And TDC Nala is right--w/o a reservation there is no guarantee that they will even let you up to get to the bar...