Bought a Diamex ALL-AVR programmer. The green device on the picture.
With my Dragon programmer I disabled the Jtag-Enable fuse of the Atxmega Xplained.
Made a small converter and now it is possible to program the Xplained board right from the Bascom-AVR IDE.
Here some pictures
The combination Atxmega Xplained, converter and Diamex programmer
The small converter.
I found the schematic here: www.nlvocables.com/blog/?p=545
Settings in Bascom-AVR.
Some additional info:
You have to power the Xplained board with a USB-cable. And after you programmed the board you have to unplug the Jtag-cable because the reset is held low by the converter.