how to conveniently upgrade with specific catalog change

Hi, all
I am doing some development based on postgres(8.x.x) and encountered a problem when doing upgrade. Normally, there are
twoways for me to do upgrade. 
    1. when new version without catalog change, I can replace the binary and restart the cluster.
    2. when new version with catalog change like add a column or a row to a system table, I can replace the binary and
turnallow_system_table_mods to all, do all the changes, then restart. 

But, when new version add a new built-in datatype, like json, which will insert a row in pg_type with specific oid, I
cannot find a simple way to do this. I look up the initdb code, it run the postgres program in bootstrap mode, feed it
datafrom postgres.bki file which support oid specification. Simplify the question, How can I do upgrade conveniently if
Ijust need to insert one row in one system table with specific oid? Can I do it in upgrade mode somehow or I need to
runsome upgrade program? 

Best Regards,
Zongtian Hou