Link to the tool: https://sirstanel.github.io/
Link to Scmdraft II http://www.stormcoast-fortress.net/cntt/software/scmdraft/download/

1. Replace text in "xxx" with desired text, also time in "x:xx" with time when the text should appear, modify secondsDelayed (-3) if you want the text to appear sooner or later.
2. Click "Generate Triggers" and copy the output
3. Open Macro Alone map in ScmDraft 2, the StarCraft map editor
4. Triggers -> Trigger Editor
5. Paste the triggers generated earlier replacing all other existing triggers
6. Click compile. The checkbox with a blue diamond next to it
7. Click "Save As" and choose a filename which represents the build order to practice