I have written a script to show an idea how to get notification based on keywords. I have a power shell script that checks new alerts for the keyword and sends notification. This is occurs outside of the Ops Mgr console, so you will not see this under recipients or subscriptions in the console. The power shell scripts get both keywords and recipients from a configuration file. After a notification is sent the custom field 1 is updated on the alert, so the script will not send multiple notification for the same alert.
You can modify this script to include more attributs from an alert, with default settings it is only searching the alert description.
All information is included in the readme file.
Download the package here.