You can't change the schema name for an intrinsic database (the database that is created with LightSwitch). Maybe you'll be able to in V3, but you can't currently do it in V1 or V2. To achieve this, you'll have to create the database in something like SSMS (SQL Server Management Studio, then attach to it as an external data source.
Seeing as you've already done all the creating in LightSwitch, you could publish it as is, then attach to it as I mentioned above. I hope you don't have screens created, because unless you want to manually edit all of the lsml, you won't be able to use the attached database in any already created screens.
Any time you need to do something "out of the ordinary" with LightSwitch's database, you need to create it outside of LightSwitch, then attach to it. Why? LightSwitch was originally created with the idea in mind that the users didn't need to know anything about SQL Server.