I don't think you can activate it from the ipad. Are you referring to the RM8/day - you have to activate by SMS using a phone. That's main reason why I stop using this Maxis - it is expensive and not so practical to use on the ipad unless you have a iphone4 to use with it to send the sms.
The best I find on prepaid is still Digi internet package
http://www.digi.com.my/internet/promo_limited_pre.html

Daily is only RM2 and a topup of RM10 gives you 5 days usage ( no limit ). The line is active for 90 days

If you bought the DIGI Internet prepaid , it is auto activated. After cut your card, insert the card . It will take few seconds to detect, you will see signal bars and DIGI at top left corner. At settings/cellular data/apn settings  set your apn  to 3gdgnet. Read the small guide to reconfirm

Just buy reload coupon, start at rm10, IE 5 days usage. You ask the shop to topup for u or you use another DIGI line and dial from phone - read the guide is all there. Dial *123*16digit number*01 your phone no#

Omg I don't believe I need to spoon feed  this as it is all in the small guide booklet