I have been hunting for this plant since you posted and started this thread. After much time looking for where I could buy one with no success, I put it on my list, hoping that one day I'll come across one.
Well that was today! I was doing an inventory of my plants and came across this plant:
Trichopilia Charles x romonensis by
MattWoelfsen, on Flickr
I did not realize I already have one! I bought it from New World Orchids back in September 2013. I remember seeing it on the shelves, Dr Glenn Lehr asked me if I had this orchid, I said no but went and bought it. It has been growing or rather existing all winter long. I repotted it three weeks ago in sphagnum moss. I guess it was instinct or something told me it was an Oncidium alliance plant and have kept it well watered.
Thank you for your information on growing this one.