Within BI 3.x it was quite easy to debug your startroutine. Pressing the sequence F7 -> F6 -> F5 brought you directly to the startroutine (code). Within BI 7.0 the “F7->F6->F5” trick doesn’t work anymore.
To debug a startroutine in BI 7.0, the following steps need to be executed:

1) Go to Display Generated Program within the transformation

2) Jump all the way down to find some startroutine coding you recognize 🙂 and place a break-point.

3) Find the load you want to debug within the DTP monitor

4) Press the debugging button

5) Execute the debugging request and the execution will stop at the break-point which has been created/set at step 2.

Big thanks go out to Freek Geldof who provided the necessary information!