You shouldn't need to broadcast passwords, you can store the in the HKN launch subroutine. I have a Newbie's Guide to HKN here. It covers how to set up resized windows, how to use arguments for automatically inputting passwords and just about everything else. You'll want to read it all, as the first half only looks at how to adjust the default HKN script. The second half is about making the script better as the default scripts are very, very basic and in some cases, such as the default Launch subroutine, problematic.

I also recently walked Nikita through setting up the window resize and the login setup here.

You may also want to look through A Tour of My HKN Script In 5 Parts as well as the various guides in the Multiboxing Vol. 1 and 2 as I try to collect various informative posts there.

As far as selecting the right account for the window, you'll need to set up Symlinks, which I go through here and here. Right now I have Cache, Data, Interface and Screenshots symlinked.

Otherwise you can use a toggle to send all keys instead of the filtered ones

Code:
//-----------------------------------------------------------
// DEFINE HOTKEYS FOR ALL KEY COMBINATIONS THAT WILL GET
// SENT TO BOTH WOWS. ADD MORE KEY COMBO'S IF YOU WANT. 
//-----------------------------------------------------------
<Hotkey ScrollLockOn A-Z, 0-9, Plus, Minus, F1-F12 except W, A, S, D, Q, E>
<SendLabel w1, w2, w3, w4, w5>
<Key %Trigger%>

<Hotkey ScrollLockOff A-Z, 0-9>
<SendLabel w1, w2, w3, w4, w5>
<Key %Trigger%>
This makes it so that if you turn scroll lock off, it will send keys a-z and 0-9 without excluding WASDQE. But, you may need to go back in and change that to use Keylists if you need to use any modified keys in your passwords {like shift+1 for !}.