CPLD Board design newbie questions

Hi, I've done a bunch of work with FPGAs in courses that I took, but in all those cases I was using either Xilinx's FPGA demoboards or an Altera board designed by my university. For my lab now I'm designing a board that will have a Xilinx CPLD on it, and not much else. I'm sort of the token EE in my lab, and having just gotten my bachelor's last year, I've never really designed a board. My main question now...I want to be able to easily reprogram the CPLD, so to access the JTAG interface I could just put some header pins on the board and wire them up to the right device pins, correct? Also, it seems to me like the board would have to be powered up, i.e. plugged into the back plane, to be programmed. This might not be so convenient as the electronics box it will be going in is pretty far away from the PC that the design is being on. Am i mistaken in that the board needs to be powered up, or can the cable supply the power? I guess a solution would be to add another header to connect to a separate, portable,