I would think if you search hard enough, you might find something. You might check out ADOdb. If PHP is able to directly talk to Access, I'd think this library would have it.
Otherwise, I'd highly recommend just exporting everything. 1000 members isn't too bad, unless you have a boat load of tables. The more tables you have, the more painful it gets. phpMyAdmin won't do this for you. You'll have to go into Access to do this part. But once exported, you should be able to use phpMyAdmin to import the data. Unless you have too much data. If so, you may need to look into MySQL command line batch importing or writing a PHP script with a large script time out value.
Another note: Access isn't designed to take a beating from multiple users (and when it does, it fails and breaks things). Export the data and import it into something else. Whatever else you select will probably run faster and be more stable...