gistfile1.xml

<!---- Adding Paypal ----->
<request method="invoice.create">
	<invoice>
		<client_id>1</client_id>
		<gateways>
			<gateway>
				<name>Paypal</name>
			</gateway>
		</gateways>
	</invoice>
</request>

<!---- Adding Paypal and Authorize.net ----->
<request method="invoice.create">
	<invoice>
		<client_id>1</client_id>
		<gateways>
			<gateway>
				<name>Paypal</name>
			</gateway>
			<gateway>
				<name>Authorize.net</name>
			</gateway>
		</gateways>
	</invoice>
</request>

<!--- Disabling all gateways --->
<request method="invoice.create">
	<invoice>
		<client_id>1</client_id>
		<gateways/>
	</invoice>
</request>