type = configurable
product id = 1300
product sku = FCC100
Attribute Code= color
Attribute Label= color
Attribute Id= 152
options value = 28,43
options label = blue,red

$product = array(
"product_id" =>"1300",
"qty" => 2,
"super_attribute" => array(152 => 28));
$result = $proxy->shoppingCartProductAdd($sessionID, $cartID, array($product));

$result = $proxy->shoppingCartProductAdd($sessionID, $cartID, array(array(
    'product_id' =>   $productID  ,
    'sku' =>  $sku  ,
    'qty' => $qty,
    'options' =>array(0 =>array('key' => $option1id ,'value' => $option1value),1       =>array('key' => $option2id ,'value' => $option2value)),

    'bundle_option' => null,
    'bundle_option_qty' => null,
    'links' => null
    )));