I'm trying to figure out how I'd explicitely change out a div.

Lets say this div is in the page.  I guess first I'd have to verify if
it's in the page:

<div class="jcarousel-prev jcarousel-prev-horizontal jcarousel-prev-
disabled jcarousel-prev-disabled-horizontal" style="display: block;"
disabled="true"/>

And if it is, I want to remove it and add this in the same place:

<div class="jcarousel-prev jcarousel-prev-horizontal" style="display:
block;" disabled="false"/>

I have not a clue how to do this.