Shell Programming and Scripting

Hello all
i have big test file that has allot of structure text something like this :
<foo1 *.html>
<blah action>
somthing 1
somthing 2
</blah>
</foo1 >

now i will like to insert 2 more lines of text below the <blah action>
so it will be like :

<foo1 *.html>
<blah action>
param1 off
param2 off
somthing 1
somthing 2
</blah>
</foo1 >

i need to be able to insert it all across the text file .
i know i can do search and replace in vi with
%s/action\>$/.........../g

but i don't know how to tell the replace command to insert line brakes ( i think this is what i need)

Code:

:%s/action\>$/&^M........../

Where ^M is entered by first entering [Control-V] and then [Control-M].