Hi,
I believe the below may be what you are looking for.
1. Create a metric group based on the Metric Expression "EM Host". I named my metric group "EM Host". Set the Metric Group Agent Expression to "(.*)\|(.*)\|(.*)"
2. Add a "Metric Data Table" element to the report.
3. Under "Data Properties", select "EM Host" as the metric group
4. Under "Display Properties", set "Table Columns" to "Text Value". What this will do is take away the default count, min value, max value away from the report as they are not applicable to a String element. This will only show the host names.
Apply the changes and preview the report. Let us know if this works for you.
Thanks,
Matt