Hello,
I did a search at www.google.com for +labview +fpga +jtag and found several relevant sites, including this one, which I thought might be the most helpful:
http://www.intellitech.com/software/eclipseboundaryscan.html
(remove the space in the URL...this entry form seems to put it there automatically)
I hope this suggestion gets you pointed in the right direction. Good luck in your search, and have a pleasant day.
Sincerely,
Darren Nattinger
Applications Engineer
National Instruments