Using Class Abilities as Custom Abilities: doable?

[Lord Magus]

I am trying to create a Gunslinger archetype that gets to select Deeds from a number of choices, instead of getting 3 pre-selected deeds. I plan on making Deeds the secondary or tertiary custom ability, depending on what's available.

Will I have to redo all the Deeds I want available (which are Class Abilities) into new separate abilities, or is there a way to use the existing Deeds as Custom Abilities (maybe by assigning a tag to all of them) ?

Thanks for the advice or practical examples I could look at.