how to root after cm10 install

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http://forum.xda-developers.com – I recently installed cm10 on my fathers S3 and everything went smooth until root checker said I did not have root access. I dont see how I missed it, I used the steps from the guide on androidauthority.com as well as the steps from the links the guide provided to install clockworkmod and cm10. My S3 is rooted with cm10 with no issue. but my fathers isnt after the install when i used the same guide. Is there a way to root on cm10 without having to wipe and install the stock rom and then root? (HowTos)