How (should I really) to create a custom strategy to be authenticated via custom authentication API

[belgoros]

I can't find any docs or examples on how to proceed if I need to authenticate a User via an external (corporate) API to let him enter a Rails application ? Should I create my custom strategy as described in strategy contribution guide or go the way described by Doorkeeper ? Event after readng and watching the available Rails screen casts, I'm still really lost. Any tips and tricks, links would be really appreciated!

Thank you.