If you do not have tickets with transportation (option when getting a package), you can take the Amtrak train to San Diego, and then go to SeaWorld from there. I haven't investigated whether they have shuttles, but someone might know. If not, maybe a taxi.
Amtrak actually has a station code for Sea World - SDS - which includes the train to San Diego (normally SAN) and then an Amtrak bus to Sea World. So go to their web site and plug in ANA => SDS.
We're looking at taking Grayline Anaheim. The bus tour leaves daily at 9:15 am and returns approx. 11 hours later. It costs $69 for both kids and adults and includes your gate admission to Sea World. You can check them out at graylineanaheim.com.