If you are trying to use a TCL file in Vivado, TCL is really used to AUTOMATE the tool. As such, if you want to "step" through, feel free to copy paste 1 line at a time out of the TCL directly into the TCL Console. Then you can control the speed of execution to the rate you want!
The TCL file you are refering to is used as a Tool Automation. If you are looking for it to go slower, we suggest you step through each step using the GUI. You are able to copy/past one command line at a time into the GUI TCL window if you are unfamiliar with how the GUI works. Unfortunatly that is all I can think of for stepping through a TCL script.
