Pretty simple to do. depending on JACE it may or may not already have BacnetIP loaded.
Cool! The Jace isn't there yet, the NAE is on-site. So I'm assuming from your post the NAE does BacnetIP? Can it do mstp also? If so, any reason you can think of that the NAE couldn't "talk" bacnet to Hw spyders?
Just be sure that if you use the JACE to serve up BACnet points to the NAE, that you've purchased the BACnet server license feature (yeah, a little awkward, I know). This will allow you to build the "export table" in the JACE, which will contain all the points you want the NAE to see.
Another point - while the NAE will do BACnet/IP, it will only do MS/TP if the correct model was purchased and installed - they come in N2, MS/TP, and combo models, so you'll have to do a little checking if you want to use it to talk directly to the Spyders. I'd be interested in seeing if that worked - NAE's are generally very flaky/finicky when talking to non-JCI controllers of any protocol.
Depending on the age of the age of the NAE you can change the type of FC bus. Recently JCI started to come up with different part number for each type of trunk and configuration. You could at one time just access the NAE and put in the N2/LON/MSTP bus. Also, if you are using MS/TP IP you will need to add a BACnet integration to the NAE in the all items tab. Good luck.
I did an aaon mstp integration this week with an nce. It went very smooth. Just insert a non fec family bacnet device and make sure you have your mac address correct under your hardware tab. This was my first with an aaon and it was pretty easy. A bacnet ip integration on the nae side is simple but not sure about the jace side.
You can still use the Jace in the same way by leaving "Routing" on in your Bacnet Network setup. Then it will route all bacnet communications just like a router would. Best of all, I don't think you would need the export licensing.