I also don't have any familiarity with any plugins like you mentioned, so I am glad you do

Funny thing is, there was a tutorial on how to build a calendar in 2.x. to 3.x....Hmmm....<searching>....
Ok, found a few things.
Hugh has a date picker on his site (free trial) which you can find here.
There is also this one by Bob Cole.
Apparently, the calendar tutorial never made it to the lessons page from what I can see, although I found several tutorials on making an html version of it.