It looks like tmsh::send-mail isn't part of the API, so you can't call it from an iCall script: https://devcentral.f5.com/wiki/TMSH.Commands.ashx
However, it looks like you can create a scheduled ASM report using tmsh::create, so you should be able to write an iApp that creates this object and update the schedule on reconfiguration. Does that help?
analytics application-security scheduled-report test_charts_scheduler {
email-addresses { me@example.com }
first-time 2015-01-16:14:00:00
frequency every-24-hours
include-total enabled
multi-leveled-report {
chart-path { attack-type application }
limit 5
time-diff last-day
view-by violation
}
next-time 2015-01-16:14:00:00
smtp-config my_smtp
}