Hi Brian,
If you are able to use CRON, a CRON expression like this will run a process (or job) at 13:00 the last Tuesday of every month.
'00 13 * * 2L '
Here's a link to Cron on wikipedia if you need it:
https://en.wikipedia.org/wiki/Cron
There are external job schedulers that are capable of setting this up for you.
Here's a link to a list of them.
List of job scheduler software - Wikipedia, the free encyclopedia
Regards,