Well, the key appears to be building a stylesheet that locks out all of the responsive stuff. Take a look at http://getbootstrap.com/examples/non-responsive/non-responsive.css for what they use to stop the page from being responsive. You could probably lift that entire sheet.
Regarding the navbar specifically, there is nothing that you can do without having a sheet like the one linked in this answer. That being said, the one thing the example doesn't do that you probably should is rip out the menu icon that will show up when the navbar collapses. That would be this bit of code:
<button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>