Martin employee guitar without truss rod !!

Hi, I acquired a Martin guitar which was made by am employee. It's probably made quite recently. The only problem is that it wasn't finished.
There is a hole for the truss rod [Thru the brace and into the neck], but alas the truss rod itself is mia. It's a beautifully made guitar but needs to be finished. also, what's the best under saddle piezo system to electrify my baby?
Can anyone illuminate me as to whether a new truss rod would be easy to install?
Thanks for all replies.