It's possible to create a "7-ports hub" using two HX2VL. You could connect the upstream port of HUB2 to one downstream port of HUB1.
There's noting special to take care of. You could refer to CY4608 design
and HX2VL hardware design guide
Note: It's recommended to provide power from external source in you design, i.e., self-power design is preferred.
Thank you very much.