Is it possible to make a player start out in caves instead of aboveground or make them spawn in random place in world even when wilderness mode is off?

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I have a mod character which's supposed to be from the caves so I thought it would be cool if he spawns somewhere randomly in caves (if the world has caves on), would this be possible via code or impossible (very hard)? I'm guessing it would be hard but just wondering, who knows maybe someone knows an easy way to do it !

If that's not possible would it be possible to make this mod char spawn in a random position aboveground even when server's not on wilderness mode instead of spawn portal?

Thanks for reading my questions, peace !!

Edited December 24, 2017 by SuperDavid