Hello Andreas,
a) First, I recommend you to try IBM DataPropagator especially if you already have got it. It must work.
Since you need to replicate data from DB2 to MySQL, DataPropagator (CAPTURE program) will read DB2 transaction log and populate replication tables on DB2 AS/400.
Then DataPropagator's APPLY program will read these tables, and replicate data to MySQL using SQL INSERT statements.
As you see, all is very simple. For DataPropagator, the source database is very important , target may be any SQL compatible database, I think.
Give it a try! Good luck :)
b) DataPropagator is very powerful tool, but due to cost reasons, you may choose more simple solutions.
You can just export data from DB2 and reload them to MySQL. Existing data transfer tools can automate this work. As I said before MySQL LOAD command allows you transfer updates only (our tool SQLWays uses this feature e.g.)
It may be effective if you do not work with very large databases. What do you think?
Best regards, Dmitry Tolpeko
SQLWays - Data, Schema, Procedures conversion tool for various databases
http://www.ispirer.com