I don't think you can. SLP can use AdvancedDisk or SharedDisk but not BasicDisk.
This is from
Designing and Implementing Backups Using Storage Lifecycle Policies
6.4.4 BasicDisk Storage Units in Storage Unit Groups
A Storage Unit Group that contains just one BasicDisk Storage Unit will behave as a BasicDisk
Storage Unit Group. Although Storage Lifecycle Policies do not work with BasicDisk Storage Units
there are no checks in the Storage Destination set up to prevent you from selecting an Storage
Unit Group that contains a BasicDisk. Care should be taken when using Storage Unit Groups in
Storage Destinations to ensure that there are no BasicDisk Storage Units within the Storage Unit
Group.