Actually, I've been trying to figure this out too.
XC needs 9.4 to run which means if you're running gateway, the only way you can play it is in an updated classic mode.But NTR won't run in Gateway Classic; only in Sysnand (which would be <9.2). I've tried using the eshop FW spoofing method to get the save off XC on NTR CFW but since the game needs 9.4 to run, the game doesn't load and the save doesn't get extracted.
Just thought I'd save the OP some cash if he was going to buy CN for this reason.
If anybody has a solution to this, I'd be very interested as well. So far, this is the only save I haven't been able to migrate from retail to GW.