Thief Style Mantling System/Tutorial?

Hi all.

I’m looking to implement a Thief style mantling system into my first person game but I cannot find a tutorial for what I want.

For those who haven’t played the games, how it works is that the player holds the jump button while moving towards a ledge they can mantle on, either from a jumping or walking position. When they hit the surface and it’s at the right height for them to mantle they’ll stop in midair and then the character will move up and forward onto the flat surface until they are stood on top of it.

I am unsure how to go about making such a system and would appreciate any tips or pointers.

Cheers!