IAmazonEC2 ec2Client = new AmazonEC2Client();
var ec2Request = new DescribeInstancesRequest();
var ec2Response = ec2Client.DescribeInstances(ec2Request);

<configSections>
    <section name="aws" type="Amazon.AWSSection, AWSSDK.Core"/>
</configSections>
<aws
    profileName="[yourprofilename]">
    <proxy host="[yourproxyIP/hostname]" port="[yourproxyport]" />
</aws>