Hi, Sam,
Of course, you can use the USB CDC as a serial COM to communicate with KL43 on FRDM-KL43Z, pls refer to schematics of FRDM-KL43, the PTA1(PTA1/UART0_RX/TPM2_CH0) and PTA2(PTA2/UART0_TX/TPM2_CH1) pins are used as the SCI port(using uart0). Pls programe the uart0 so that it can communicate as serial port.
I suggest you download SDK2.0 based on KL43 from the website:
http://www.nxp.com/ksdk
You can use the Hello_World as the example.
C:\Freescale\SDK2.0KL43Z256\boards\frdmkl43z\demo_apps\hello_world in SDK2.0 tools
Hope it can help you
BR
Xiangjun Rong