This is a script that copies a customer from one magento store to another. The two stores must have the same products.
Contact dan at edenwired dot com with questions/requests, or contact me through github.
First, copy config_db.php.tmpl to config.php.
Next, configure the source and target databases in config_db.php.
Then, set the id of the customer you want to transfer in magento_alter.php.
Lastly, just run
php ./magento_alter.php
This software is distributed with ABSOLUTELY NO WARRANTY! It may screw up your Magento store - that's your responsibility.
BACKUP!
TEST THIS FIRST WITH A TEST INSTALLATION OF THE TARGET DATABASE
I don't know why the sales_flat_order table has two unique keys, but if you look for these lines:
unset( $row['entity_id'] );
unset( $row['increment_id'] );
you'll see what I'm talking about.
For now, I'm grabbing the max(increment_id) + 1 from the target database's sales_flat_order table and using that. I'm guessing magento has a more sophisticated way to do this.