Download the DTX-Controller from http://rpbirt.com/zedfiles-archive/DTX/
(updated 10/3/2011) and follow the instructions in the readme.
I would suggest creating a main folder on the drive THEN unpacking a XAMPP.zip file into it as a sub-folder. The DTX-controller is placed in the xampp/ along with the dtx.ini.
If you want a stable install, use the alternative porting as outlined in the readme! The ports: 6060/6080 have been tested enough times that it would be a very rare exception for there to be a conflict.
As Izzy has stated before, it is important to give some feedback on DTX... while there are many downloads, there has not been a lot of input in quite a while.