StaffIt's not possible to access all the targets from the load test script yet. I hope to improve this in one of the next releases.
But you could do anything you want with the current functionality. You could use events and setup of the test case in beforeTestCase. LoadUI context could be used as a global storage and SoapUI context could be used as a virtual user storage.
And the shared datasource thing is not working the way you described it or at least i did not understand this correctly. Each time test step requested a new line shared datasource returns the next one. Its not isolated anyhow. It became a global object available for each virtual user. It'll be probably much easy to understand it's work via logging data in afterTestStep loadUI event.
