We get a lot of emails and questions here at Publisher Tower concerning charts and how to do X. I write about some of the solutions here if I think they could be useful to a wider audience but its tough to document everything for everyone's specific features.
The chart dialog in the template builder gets you so far but there are cases where you are going to have to get into the code to make things work the way you want them to. I have documented a bunch which I have pulled together as links below. But if you do venture into the chart code, where do you start?
I have re-documented the location of the chart DTD document recently as it disappeared from OTN and having bugged a few people about it, its still not there, c'est la vie. But those of you with the Template Builder for Word (TB) have your own copy you can refer to. Just dig into your TB install directory and look for the dvt-jclient.jar (11g) or bipres.jar (10g) files open them with a zip utility a dig down through the directories to oracle\dss\graph\.
There you will find the fabled and rare, graph.dtd ... this is the golden fleece of the BIP charting world. In it, you will find secrets beyond your imagination, treasures beyond compare ... OK, its not that exciting but there is a lot of charting info to be gleaned. There is not much in the way of comments but you can at least look up features and then see what attributes they will need to achieve your needs.
Just remember, Word has almost unlimited undo's, just get stuck in a try stuff out you are not going to break anything!