If you haven't resolved this yet, I'd be happy to help. I just finished doing a bit of customization myself.
The template file used to display the product is "wpsc-single_product.php" and includes a call to
do_action( 'wpsc_product_addon_after_descr', wpsc_the_product_id() );.
To change where the Personalization fields are displayed, you can edit your template file and relocate that bit of code.
Check WP Admin > Settings > Store > Presentation and look for "wpsc-single_product.php" in the Advanced Theme Settings box. If it has a check mark next to it, you can edit the file in your active theme's folder. WP e-Commerce Theme Customization
The other option is to modify the WPEC Personalize plugin and change which action it hooks into. Look for
If this solves your issue, or if you solved it another way, I hope you will consider posting your solution and marking the topic resolved.