Here's a more complete guide to getting WiFi going on rPi (Sorry if there's any bad blood between here and there... but it's a good howto):
https://forums.butterflylabs.com/showwiki.php?title=Tutorials:Raspberry+Pi+-+Mining+with+MinePeon&viewfull=1&page=4&do=comments#post38317

And, all I did to install ntp was:
$ sudo pacman -S ntp

it asked to uninstall openntpd, installed ntp, and after a reboot, time sync was resovled.

HTH!