I know I saw this type of thing once upon a time back in the days of the official TS2 forums. Any help would be appreciated. I scoured this site and others the best I could and all I could find was this http://www.modthesims.info/download.php?t=250412 which allows more than just Uni sims to walk by on Uni lots.

I'm prepping to make an awesome realistic city/town from scratch and this type of thing would help make my project more realistic.

With Inteen, you can have anyone* living in the Uni subhood...but you cannot just send them there to buy a house. You'd first need a student already living there I guess, who would invite another sim..and maybe move that sim in ?
I am not sure, so go read about it.
I think the pack that allows this is called : InTeenimater_FlavorPak_ResidentialGraduates.

Well, it's not quite what I was remembering, but it is a step forward. Thank you, Rosebine. I'll be using Inteen in my hood anyway, so it will work for the interim.

Just to expand a little: With Inteen and the Residential Graduates flavor pak, you can move Sims of any age, infant through elder, in with a YA student, yes, and they will age appropriately (Although the YA won't age, of course) and school buses will show up for children and carpools will show up for anyone who's employed, etc. etc.. However, they must (at least initially) be moved in WITH a YA, not by themselves. I don't think you can move them out by themselves to the Uni family bin, either. To get around this, what you CAN do is move the desired non-YA(s) in with the YA, then move only the YA out to a new lot, then teleport over the non-YA(s) (or call and invite them over, I suppose), move them into the new lot, then move the YA out. (Or it might be possible to move out the YA with the desired non-YA(s) and then move out the YA alone. I've never done it that way; I should try it. ) Then, you'll have non-YAs living on a Uni campus without a YA in the household, basically using the same technique as getting a teen to live alone in a main neighborhood. Their cash-on-hand will probably be messed up after all the moving around, but you can adjust that in various ways.

So, in short, this will work, but unless you want your non-YA(s) living on the same lot as the YA, then it takes a bit of finagling to get the various Sims where you want them to be.

You might want to take a look at Squinge's college mega pack: http://www.insimenator.org/index.php/topic,96190.0.html. One of it's feature's is to allow YAs to attend college while still living in the main hood