Neat idea.
Unfortunately, the best tutorials are the ones on SimPE itself and at MTS2. I would look at Echo, AdidasSG2, and Carrigon tutorials. Dizzy had start tutorials over at the now defunct variousimmers.net I don't know what purpose it serves to mention things that don't exist anymore, other than to bring that to light.
I suppose you could hope that he might have copies somewhere and be willing to repost them in the Bowels of Trogdor (where you could read them, but won't be able to post until you are as big as Pescado's beefy arm
)
Anyhew... start with Carrigon's tutorial(s). They are old, but I think they are extremely helpful because of the diagrams. Yes, they don't apply anymore, but it forces you to familiarize yourself with the "new" version of SimPE. She names and labels things, so you'd just have to hunt and peck for the corresponding part in the "new" version.
I think the best way to start is by running through a couple of those tutorials, get familiar with some terms and "code" and SimPE, and then recreate the objects in the tutes.
Since your ultimate end goal is to create a "new" object with "new" options, Carrigon's tutorials should be very helpful. Basically, you would be cloning one of the mirrors, and then you would be adding new options to it. From those tutes, you should be able to figure out how to add the menu options, and then link the BHAVs behind them.
From your idea, I would just duplicate one of the existing interactions (like Practice Speech or Practice Romance) and then change the "skill" that is increasing to be one of the appropriate personality traits you want to adjust. For example, if you cloned the practice romance, complete with the self kissy animations, you could make that increase outgoing. Once you have that working, then you can get a bit more complex, figure out how to lift other anims, like say from lecturing or arguing, and make that increase grouchiness or seriousness. That will probably be a bit more advanced, and require you to look at other parts of the object code.
For that, you should get those helpful dizzy tools or at least disaSim2 (if you don't want to install all those pythony type pre-requisites). Then you can just dump the object code into html files. I highly suggest using firefox tho, to open them up. IE just chokes and dies on them.
Besides, the search tool in firefox is very useful.
BHAV editing really actually isn't all that hard. So long as you have an alogrithmic, binary, boolean mindset and don't mind wading through all the spaghetti.
Ste