I'm thinking that the best in game interface would be either a computer in the players home or the pipboy itself. I would personally like it to be from the pipboy because it would be akin to pulling out your smartphone and writing in a journal on that device.

If anyone can point me towards learning how to create this myself; I would be appreciative.

I would love to see some old makeshift journal mod. I loved Oblivion's but sadly there are none of the sort for Fallout.

Thanks for the response, Roughnecks! I'd begun to feel as if the idea had no merit to anyone but myself.
I just kept reading about 'immersion' and how important that was to people and I was thinking about alt-tabbing to write a journal of sorts in notepad or something when it suddenly hit me, how immersion breaking is that and wouldn't it be great to journal in game...
So, I'm still trying to figure out how it might be done. Never done any modding, however, so it's gonna take me some time.

The only way I think it could be done is through the " ~" console comand ??? Unless you had a bunch of pre written journal entries to be triggered by certain events. Hence just add notes.
But I think that would be to cumbersome for the mod writer and not enough emersive for the game player imo. Although you might find it fun just in the figureing out how to mod it???

When gameplay becomes boreing ... trying to figure out how to change it can be fun