To perform a live search type into the box "Please Enter your search term". After two letters have been entered you will see a list of all the names that start with those two letters.
[[File:Searchresults2.png|800px]]
You can now click on the record you would like to insert and the fields on the form will be populated with the specified values.
[[File:Searchandinsert.png|800px]]
This is how to get a simple ajax live search call working on a form. It can be changed around to suit your needs.