@LT_Jason, 

Is it possible to utilize custom JavaScript Libraries within a SmartForm without the need for creating a custom control?

Yes, but I find it difficult to use the tiny window of a data label to use with excessive code, but that is a personal preference, I would recommend writing and testing code somewhere else and only adding it to the smartform (datalabel, expression) when it all works. 

To test out if it works I used a simple JQuery example from W3Schools, Hide_Show

Created a view with a 1X1 layout. 

Added a single data label, added an expression to the datalabel

Copy and Paste all the code into the box of the expression (Why I would not write this much code in a smartform directly, only a tiny bit is viewable):

More code does show in the Preview Pane at the bottom:

Once the code is in the Expression on the Data Label, make sure to check the Literal check box.

The view is a very unassuming in Edit Layout mode: 

Save and view in runtime.

Runtime: 

Clicking the button will make the text hide, which means jQuery is working. 

I did not test MegaMenu.

Also I only tested that jQuery works, I did not have the jQuery code interact with anything outside of the code that I inserted. Every part of the code that I put in is self contained and only affects items inside it's own context. If you would like to get more elegant with your solution I recommend that you look into using a custom control. 

But just to answer your first question, "Is it possible to utilize custom JavaScript Libraries within a SmartForm, without the need for creating a custom control?" The short answer is Yes it is Possible.  To create something that interacts with more controls and functions in the smartform? I don't know. Please try it out and post your results. 

Chadg

I just found an example in this blog:

http://blog.velocity-it.com/2014/10/07/how-to-call-jquery-or-javascript-code-in-a-k2-smartform/

new link:

https://www.velocity-it.com/synergy/k2/how-to-call-jquery-or-javascript-code-in-a-k2-smartform/