Update for others that might want to know.

Left wc in the box but open for them to inspect. Got to airport and got a airport wc. Went to counter and told them I had a wc in a box and asked if they preferred to check it with/without the box. The counter agent told me to leave it in the box and had me sign a damage waiver. I had printed off the wc transport form from the united website but since it was in the box he do not want it. He didn't look in the box, just told me it had to be sealed. Tagged and off it went. Was delivered to me at my destination.

Much easier than lugging it through the airport although when departing from denver for a connecting flight he had a bit of a struggle getting down the regional hallway (puddle jumper area where they share a common upstairs counter and than have walk down a long hallway to get to the actual plane.)