You can unlock a Cheat called 'Play as Deadwing!' then enable it in the secrets menu! Note: You cannot fly!
Warp to Asylum: Playrooms and find the rooms in the hallway that lead to a play
pen area and pool table room. Hop Onto the Pool Table.
Go to the Temple Of Blood (Nager) and enter the small bonus room reached from the platform that is knocked down by the large hammer. The "Secret Activated" message will appear when you walk in the room.
From the teddy bear save point go right through one of the automatic wooden doors located on the ramp of ledges. Once you knock over the platform (with a hidden switch) jump to the ledge from the right angle (just barely jump) and after a few (or several) tries Shadowman will grab the edge without hitting his head on the top.