Currently, Booster Pack pathways are only provided based upon the results of the initial Benchmark Assessment and are not available as a separate pathway. However, an Educator can certainly create and assign a custom pathway to a student if they so choose.
How to customize a pathway, please see article Create a Custom Pathway
To further customize the pathway, please see article Add/Remove/Move Lessons in a Custom Pathway
To assign this new pathway, please see article Assign a Pathway