howto update meterialized view log's pctused larger than 0 on oracle 9.2.0.1

Hi I want to create a meterialized view log with pctused larger than 0, but failed. My oracle is 9.2.0.1. First, I use create materialized view log on tbl_term_inf tablespace tjsplog; then through toad, I find the pctused is 0. This will cause my table space grow fill under large pressure.