After doing some research on my own on a Warlord server for quite some time, I was able to conclude at least one way to get inside the hotel since I experienced this myself. There are likely many other ways to get inside, but I only know of one.
Here goes. When in one of those narrow Warlord corridors, try to angle yourself so that you die with your feet sticking outside of the hallway. Now have a medic revive you. Apparently, you rise from your feet when you die, so you should now be in a hall wall.
When in the wall, you have a very small moving space. Move too much and you automatically die. You can see inside the hall, and outside the palace, so can easily rack up some kills. I don't use this tatic, however,