That would depend on your particular converter.
Personally, I've used Access to open up tables on our MySQL server many times (using MyODBC) and created my own update functions. It isn't that difficult, especially if one table is updated online and another is updated offline.
In doing a few quick searches,
this one caught my eye as possibly being something that would perhaps do what you want, and it had the added feature of being able to schedule the updates between the databases to run automagically. Being shareware, I'd try it out and see if it does what you need. The price to purchase seemed reasonable, too.
There were quite a few others that looked promising as well, but it all boils down to your exact needs. Google seemed to give lots of decent results on the first several pages.
Brian.