I think your question is if you can use a live search API 2.0 AppID with the 1.1 SOAP endpoint. Unfortunately this is not possible. Even though API 1.1 is still fully maintained and is not going away any time soon ( though you cannot get any more 1.1 AppIDs) , we recommend that our customers use API 2.0 for any new applications.
To help you get started with using the 2.0 end point, please refer to the documentation on MSDN at http://msdn.microsoft.com/en-us/library/dd251056.aspx.
If you have any questions, please post a question on this forum and we are here to help.
Thanks
Roopali