Thanks for posting!
Jason should be online in a few hours. In the meantime, I've edited the script to push to custom Text widgets as well. You can find the modified script here:
The steps will be the same as for the other widget types. Here's a sample Google Sheet I created to push to a Text widget:
As mentioned in our custom widgets developer docs, you can pass 1 for 'alert' and 1 for 'info' by adding it to the Column B cells in the Google Sheet. If nothing is passed, the default 0 will be sent and no icon will be added.
Here's a GIF showing how the widget would display: