I'd like to, but I wrote it on company time and hence don't actually have the right to distribute it.

I will say that the trickiest bits were extracting the exact information from the database, and figuring out the how to make arrows point to and from individual fields, instead of from the table in general.

Getting tables and fields from PostgreSQL:

    select 
        table_schema,
        table_schema || '.' || table_name as qualified_table, 
        column_name, 
        data_type 
    from information_schema.columns 
    order by table_schema, table_name, ordinal_position;

Getting foreign-key information from PostgreSQL:

    select
        kcu.table_schema,
        kcu.table_schema || '.' || kcu.table_name as qualified_table,
        kcu.column_name,
        ccu.table_schema as referenced_table_schema,
        ccu.table_schema || '.' || ccu.table_name 
            as referenced_qualified_table,
        ccu.column_name as referenced_column_name
    from information_schema.constraint_column_usage as ccu
        join information_schema.key_column_usage as kcu
        using (constraint_catalog, constraint_schema, constraint_name)
    where ccu.table_schema != kcu.table_schema 
        or ccu.table_name != kcu.table_name;

As for the DOT output, I wound up using their HTML table support, generating a unique name for each cell in the table (port="blah" on each td element) and defining the foreign key arrows as going from table1:field1:e to table2:field2:w when table1.field1 is a foreign key referencing table2.field2.