move from mysql to postgresql

Hello,

we're going to switch from mysql (ver. 5.0.26) to PostgreSQL (OS:
opensuse 10.3).
The mysql database includes several instances, and we only want to
migrate the bugzilla instance to Postgres (yes, it's the bugzilla
backend...).
What are the preferred steps to perform this migration ? ("cost free"
solutions are highly appreciated ;-) ).

thanks in advance ...GERD...