Plugin Version: 2.3 (Compatible with 3.9.1 and older versions of WP eCommerce plugin)
A WP E-Commerce payment gateway to process payments using the QuickBooks Merchant Services. This plug-in uses the WP e-Commerce Merchant API 2.0 to process payments through Quickbooks Merchant Services.
The QBMS payment gateway enables the shop owner to use the QuickBooks Merchant Services from Intuit.
First go to your WordPress Admin Panel and click on Plugins » Add New Plugins > Add New > Upload.
QBMS plug-in for WP e-Commerce
Make sure that you click on Activate the plugin, now you have installed the WordPress plugin.
Go to the WPEC store settings link, choose Payment Options and put a check next to Quickbooks Merchant Services and click update.
Select the Quickbooks Merchant Services from the dropdown, enter your Connection Ticket and click update.
Not sure if your website meets these requirements? User ServerBuddy to check your current server configuration. Get ServerBuddy over at pluginbuddy.com