Customize existing fields in Data Export reports?

I am currently running  a daily test via testRunner.bat and saving the results in XML via the Data Export Reports option. There are two customizations I'd like to make to the testSuiteResults.xml file that is generated, one at the test case level and another at the test step level.

Each <testCase> node has a <startTime> element that lists the hour, minute, and second the test case was started. I'd like to also include the date, so instead of hh:mm:ss format, I'd like it to be yyyy-MM-dd hh:mm:ss

Likewise, each test step has a <result> node with a <started> element that lists the hour, minute, second, and millisecond the step was started. I'd like to also include the date, so instead of hh:MM:ss.sss, I'd like to have yyyy-MM-dd hh:mm:ss.sss

Is this possible? I've read through the documentation, and I attempted to substitute my own parameter into the 'TestStepResultsReport.jrxml' file, but to no avail.