Hey Scott....sorry to hear of this situation with your prized Italian Cypress.
It's an interesting tree from an architectural viewpoint as long as they stay healthy....but boy howdy when they have problems...it screws everything up!
I don't really use them because of this - too much risk for the "reward".
If indeed you have borers you need an insecticide that is systemic...meaning it will be taken up by the plant into it's vascular system where it can be better assimilated by your pest.
This is a systemic insecticide product I have used that might be worth a look:
Zylam Liquid Insecticide
I use it for Asiactic Scale on Sagos and it works pretty good. You can apply it by spraying it on the foliage or drench the root ball area with it...check instructions for more detail. It's a concentrate so check rates too. This quart will go pretty far when diluted.
From what I understand Italian Cypress can also be prone to fungus so you may want to take a look at that as well. The problem is they are native to the arid regions of Europe and when grown in the humidity we have in some of our areas, they develop fungal problems. Of course for that you would want to spray a fungicide.
If you have an extension service there, they may be able to offer their input as well.
Hope this helps.....please keep us posted....