I will provide a simpler and even better method, tools needed, a phone (any) whatsapp ipa, retinapad (cydia).

1. Install whatsapp on your ipad.
2. Install retinapad and go to setting>retinapad> under system information select fake machine and hardware name. Enable whatsapp for retinapad as well.
3. Key in your phone number on whatsapp and wait for sms code.
4. Voila you're done. Enjoy whatsapp on ipad.

oh forgot to mention that its for jailbroken device

This post has been edited by benl40: May 22 2013, 12:08 PM