If you add the following relevance, then each computer will only run it on a particular day of the week:
exists (it) whose(it = (it as string) of current day_of_week ) of tuple string items (computer id mod 7) of "Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday"
Then if you use something like @jmaple recommended, then it will only run it if it hasn’t run it for the past 10 days:
not exists files "C:\Windows\Temp\scan.txt" whose( (now - modification time of it) > 10*day )
But instead of using the file
"C:\Windows\Temp\scan.txt" you could use one already being written to by the ILMT scanner, particularly if it is already using a log file somewhere.
Also, you could add all of this relevance to a baseline, then add the ILMT scanner task to the baseline. This would allow you to add these constraints to the scanner without the need to modify the scanner task as provided by IBM.
Then just run the baseline and it will automatically cause all computers to run it every 2 weeks on a particular day in a randomized distribution.
You would set this to reapply every 7 days. The log file constraint would prevent it from running every 7 days and it would instead run every 14 days.