How to? Feed keys to firefox (Yahoo Mail) window

How would I do this please? I remember someone posted this before but can't locate it.

Thoughts so far:
= begin BTM
Goto :here

1 - switch to FF Window

2 - verify that Yahoo is in descrption

3 - feed Ctrl-A, M, zero, and delay of 15 seconds, repeatedly


= end BTM

Thank you in advance