Change Data Capture - End LSN Where does it live?

Hello all,

I need some help on how to handle this.   We have a database that has all the system CT change tables.   However, we have an issue where I cannot enable CDC on the database for reasons with replication etc.   What I need to do is insert manually to the CT tables and I have found a function to increment the end lsn.   The thing I need to figure out is can I manually update that end lsn for a change table in the database and if so where does it live in the system tables etc?  In am trying to mimic what CDC does on CT table insert, update delete etc.