http://msdn.microsoft.com/en-us/library/jj820152.aspx
According to the above article, it looks like you can now call SSIS packages from TSQL without jumping through hoops like creating an agent job and using sp_start_job or using xp_cmdshell to call dtexec.
It looks like the first thing you do is use this proc, catalog.create_execution
There are several paramters to this and I'm not sure how you determine the values for them. For example, where do you get the @package_name and @folder_name values?
Based on some other articles I came across in my research, it seems the valid values for this are contained in
SELECT * FROM [SSISDB].internal.packages
and
SELECT * FROM [SSISDB].internal.folders
But when run these, I get nothing. But I do have one package I deployed to msdb and I can see it. Is there a specific way I need to deploy a package to be able to do this? The article does describe some special way to deploy and I am not sure if that is a requirement.