You need to write your own jbosscmp-jdbc.xml which overwrites then standardjbosscmp-jdbc.xml -Tag.
<!-- your datasource -->
<!-- default mapping from standardjbosscmp-jdbc.xml -->
Thank's , it's working now. The <datasource-mapping> is one of many problems that I have to figure out in order to get it works. But why I can still use <type-mapping> instead of <datasource-mapping> and still works fine????