It's probably more about overcoming your fear of the c-rail or c-box. It's really not much difficult than a regular box. Just give it a shot. Go slowly at first to just get comfortable hopping onto the feature flat based. Without speed you'll slide off the feature immediately, but once you know how it feels to hop on, you will have much more courage to go faster. To finish a C-Box or c-rail, you'd have to go a little bit faster than you normall would when doing a normal 50-50 off a box. As long as you are already comfortable doing board slides and 50-50 off regular boxes or rails, the c-box should be a piece of cake for you.