@leodb Typically the only part of your scode that is customized for your installation is the plugins and modules section. The core code of scode is the same for all Adobe customers. Here is a step-by-step guide for setting up Adobe Analytics, including how to add the plugins and modules code as extensions. Hope that helps!
If you are looking to change the scode version from other than what Tealium has provided in the drop down list (like below image 1), if my understanding is correct, then you need to make changes in the tag template.
Steps to change custom scode/app measurement version:
Note: If you are not comfortable doing the template changes please reach out Tealium AM who can help you engaging an Tealium support expert.
Hope this helps.