how to attached the action

how to attached the action to behavior during the run time. ?

..... use script, if there is no action in your script, there will be no actior in behavior panel. File - Map properties - Add script

definately This_Entity = ent_create("someone.mdl", pos_vec, Action_Name);

and maybe This_Entity.event = Action_Name;

also
me = This_Entity;
Action_Name();