If you're going to continue down the bootstrap path, you could take a look here: jsfiddle - remote URI in Bootstrap 2.3.2 modal
Note that the URL will need to be on the same domain (though you mentioned it is "internal") or your domain will need to be allowed by the remote site's Access-Control-Allow-Origin settings. So keep in mind that the fiddle demo can't actually load content from example.com.
<button type="button" class="btn" data-toggle="modal" data-target="#myModal" data-remote="http://example.com">Launch modal</button>
<div id="myModal" class="modal hide fade">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-hidden="true"> × </button>
<h3 id="myModalLabel">Modal header</h3>
</div>
<div class="modal-body">
<!-- remote content will be inserted here via jQuery load() -->
</div>
<div class="modal-footer">
<button class="btn" data-dismiss="modal" aria-hidden="true">Close</button>
</div>
</div>
You don't need to write any custom JavaScript for this - Bootstrap will know what to do based on the data-attributes like data-remote="http://example.com/whatever" and data-target="#myModal" etc.
See the relevant section of the Bootstrap modal docs for more info...
Edit: It turns out that changing the remote URL dynamically isn't as easy as it could be. Hopefully this answer will help you further.
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