I got it working, but it was a struggle. Try this:

Get your .vcf file ready. Open it up in a text editor.

Replace "BEGIN:VCARD" with "ADD VCARD BEGIN:VCARD" (don't use the quotes)

Next, replace "END:VCARD" with "END:VCARD
QUIT" (please note that I used a carriage return in there. Find a text editor that allows you to search and replace with regular expressions.

Now run: gpesyncd < yourfile.vcf

Please tell me this works. I actually went one step farther to get it to work (I used a short perl script to split each address into separate files). If you don't have to do that, so much better. If you need it, I'll gladly post the script.