Multi-line regex replacement in apache

I need to do multi-line replacement in apache2, an mod-substitute only does single line matching AFAIK.

I need to be able to do something like this:

replace

<script>
foo = x;
bar = y;
alert(x + y);
</script>

with

<script>
alert("I'm someone else!");
</script>

Is there a way to do this with apache?