cast and set target

[upyursh]

hey all, first time poster, first time addon developer

I am going to buy Wow Programming but for now will ask the community for some help

Basically what I'm looking to do is "intercept" a cast of a particular spell and then set the target for the spell.

I will eventually have it so it will cast on mouseover if available, or cast to target, or cast to self

any help would be greater appreciated