1) Create a media pool called “Weekly” with retention period equal to 4 weeks.
2) Create a backup to tape job called “Weekly” and point to the “Weekly” media pool and schedule it to run on weekly basis.
3) Create a media pool called “Monthly” with retention period equal to ~36 months.
4) Create a backup to tape job called “Monthly” and point to the “Monthly” media pool and schedule it to run on monthly basis.
Schedule both backup to tape jobs to run on the same day (say, on Sunday). Since you want to have only full backup on tapes, in the settings of both media pools disable process incremental option and select Sunday as a day for synthesized full backup creation
This way, once a week (and once a month), backup server will synthetically create a full backup directly on tapes. However, both weekly and monthly jobs will take place on the last day of month, as besides scripting there is no way to let one job supersede the other one.
Also, if I were you, I'd wait until patch#2 is released, as it's supposed to fix different problems related to synthesized full backup.