1993 Acura Vigor ignition

I need to replace my ignition (keys were lost) I was told only the lock tumbler (?) was what needed to be replaced...what needs to be taken off? Seems there is a little screw in the old one, however it seems impossible to take off, there are too many parts of the steering column above it...is this all we need to get to? If so how do we get to it?

THANKS