Hello Jon,
I use following approach:
1. Enabling of JavaScript debugging in your IE.
2. Putting debugger; directive to place where you want to put a breakpoint like:
function DoSomething(){
debugger;
//Your code behind
}
3. Opening your CRM form.
4. Activation of IE Developer Tools through f12.
5. Refresh form and your breakpoint will be hit.
Dynamics CRM MVP/ Technical Evangelist at <a href="http://www.slickdata.com"> SlickData LLC</a><br/> <a href="http://a33ik.blogspot.com">My blog</a>