I have tried to run USB Device CDC PE project of USB stack v4.1.1 with KwikStik-K40(Rev.5) board, which works on KwikStik-K40 board. There only need do a very few change and run that demo based on that project.
KwikStik-K40 board use 4MHz crystal as PLL refer clock, there only need to change external refer clock at PE CPU component.
More detailed info, please check attached picture.

I use the USB Device DCD PE project located at USB Stack V4.1.1 default installtion path:
C:\Freescale\Freescale USB Stack v4.1.1\ProcessorExpert\Examples\Device\CDC\USB_CDC_DEVICE_K40_PEx
Please check below picture about the virtual serial port info:

Wish it helps.
Best regards,
Ma Hui