Not sure if there's a way around it.
It have Yakima cross bars and it works great with my Thule Cargo box.
I was told that you can replace those newThule clamp system with the old clamp system from the old style Thule boxes like mine. I have the Cascade XT 1500. You will need to order the Quick Snap mount and the Ubolt. The Ubolt secures around any type of cross bars.
Thule Part# 05071
Hardware Bag QuickSnap $153.00
Not sure if this will fit your box but you can check with Thule to be sure
www.thuleracks.com
This is a cheaper alternative than getting a new crossbar system.
Hope it works for you. Good luck