ISIS route summarization

In a level2 only ISIS network (not using multiple areas due to MPLS limitations), is there a better method for handling aggregate routes than creating an aggregate and redistributing it into ISIS for each router? Primarily Cisco/Juniper based. Cisco I believe has an aggregate option in ISIS (similar to OSPF) and Juniper has a separate aggregate function which can be distributed into ISIS. Neither can do summarization per say unless they cross between levels; unless I'm mistaken. Offlist input is fine. Just trying to double check my brain while setting up IPv6 on the access edges. Link state does have it's limitations. ;) -Jack