RTC report - Work Progress

Hi,

I found usefull examples for RTC reports on your site:

https://jazz.net/wiki/bin/view/Main/ReportsCentral

One of them was very helpfull to me, it's Work Progress report. It shows nice way of organizing top level work items and its children.

My question is: How can I handle some custom attribute in it? Basicly, I want to add custom attribute to an existing report design.
In table LIVE_WORKITEM_CNT there is only one attribut which you can use to get for example string custom attribute. I have more than three custom attributes, and I would like to know how to get other and enroll them in existing report.

Thanks folks,
hope somone will reply to my post.
:)