Can I transition from 3 years out of school to a master's in computer science? To erase any confusion, this question is geared entirely towards requirements and expectations of academicians. I am not asking for recommendations for universities or research topics, nor am I asking about preparation for a non-academic career. Additionally, I am speaking from a United States point of view.

Briefly, here is my backstory. A few years ago I graduated with a bachelor's in computer science. During that time I took a part-time adjunct instructor position with a local community college, where I quickly discovered that I loved teaching and the academic environment. In short, I have decided that I would like to make it a full-time career.

On to my question/concern... I am currently looking into research-focused masters degree programs so that one day I can pursue a doctoral degree. I have discovered that a lot of the computer science masters degree programs can require a certain level of mathematical knowledge or even taking research focused math classes.

Is there anything I need to do in order to prepare for my CS masters degree journey in terms of brushing up on mathematics, or other subject areas for that matter? Is it possible to sign up for a program anyway, and just go back through some of my books and notes on an "as needed" basis? I would prefer the second option, not sure if either is possible at this point!
Sure it's possible and some small fraction of people have industry experience (or teaching experience or military service or what have you).  Has always been this way.  It's a minority but normal.  (Actually in good MBA programs its the expectation.  And in law and medicine its very normal, not as rare.  In research it's rare but just because of the population not going that way, not because of schools discouraging it.)

In terms of math prep, I donno.  Guess you should look at different programs and talk to them (good chance to talk about other things in general also).  Maybe there are programs where it matters more/less your math background. Maybe you can get some individual calibration on your specifics, which this forum sometimes discourages.

Finally, your title and then question text itself are a little confusing.  Are you asking about math requirements for CS MS (which would be an issue regardless of your interregnum) or for how the interregnum is looked at.