After many weeks of searching various sites and documentation from Blizzard, I finally have a finished product. Feel free to share. Here are also some links of note.
You will first need to go to the main Battle.net developers page and create an application using your account credentials. This will give you a ClientSecret and ClientID used in the OAuth method of accessing the APIs.
https://develop.battle.net/documentation/battle-net/oauth-apis
Once you have them, you can plug them into your own script and start using the following APIs.
https://develop.battle.net/documentation/world-of-warcraft/profile-apis
Here is the script I finally came up with to pull my reputations.
https://github.com/loatswil/PowerWOW/blob/master/Get-WowRep.ps1
Hope this helps!
