Code:
<Label Joe local SendWin WoW1>

<KeyList TTL 1-9>

<Template PFTL>
<hotkey %1%>
<Toggle>
<SendFocusWin>
<Key %2%>
<Wait 500>
<SetToggle 1 Hotkey %Trigger%>
<Toggle>
<SendFocusWin>
<Key %Trigger%>
<Cancel>
<EndTemplate>

<ApplyTemplate PFTL TTL B>

<MovementHotKey Left, Right, Up, Down>
<SendLabel Joe>
<Key %Trigger%>
Using the above code i am able to get the rapid alternating b1b1b1b2b2b2b2b3 etc, while moving without issue. It has a 500ms timeout and will always start with the assist key first after the timeout.
This should get you closer, if it doesn't work for you let me know what's happening, I'll try to work something out.
I just wrote the template to quickly make the number row work that way...