To install the Woocommerce payment gateway plugin, first copy /gateways/woo_satsale.php to your Wordpress site in wp-content/plugins/. If you're using the browser interface, you'll need to compress the file before uploading.
Next, in your Wordpress admin area, go to the plugins section and activate SatSale. Then go to the Woocommerce settings and the "Payments" tab. Enable SatSale as a payment gateway.
Click 'Set Up'/'Manage' and fill out the required fields and point towards your SatSale instance. You will need to copy the contents of SatSale/SatSale_API_key into your API key field. This is generated after running SatSale for the first time.
Now you should be able to view SatSale as an option in your checkout:
That's it! Please reach out if there are some further features you desire in this plugin.