Can you score on a kickoff in soccer?

YES

According to the 2009/2010 version of the Laws of the Game as regulated by F.I.F.A., under Law 8- The Start and Restart of Play (page 27 in the official "Laws of the Game") under the heading "Kick-off" it states:

"A goal may be scored directly from the kick-off."

You may verify my answer by going to www.fifa.com and download the Laws of the Game pdf file.
Yes you totally can do that.