Foreach array dentro de outro array no php

Como eu posso gerar com o php esse array para fazer uma transação de pagamento pelo Pagseguro?

$params = array(
'email' => $PAGSEGURO_EMAIL,
'token' => $PAGSEGURO_TOKEN,
'creditCardToken' => $creditCardToken,
'senderHash' => $senderHash,
'receiverEmail' => $PAGSEGURO_EMAIL,
'paymentMode' => 'default',
'paymentMethod' => 'creditCard',
'currency' => 'BRL',
// 'extraAmount' => '1.00',

'itemId1' => '0001',
'itemDescription1' => 'PHP Test',
//'itemAmount1' => $numero,
'itemAmount1' => '1.00',

 'itemQuantity1' => 1,

 'itemId2' => '0002',
 'itemDescription2' => 'PHP Test2',
 //'itemAmount2' => $numero,
 'itemAmount2' => '1.00',
 'itemQuantity2' => 1,

 'reference' => 'REF1234',
 'senderName' => $senderName,
 'senderCPF' => $senderCPF,
 'senderAreaCode' => 83,
 'senderPhone' => $senderPhone,
 'senderEmail' => $senderEmail,
 'shippingAddressStreet' => $shippingAddressStreet,
 'shippingAddressNumber' => $shippingAddressNumber,
 'shippingAddressDistrict' => $shippingAddressDistrict,
 'shippingAddressPostalCode' => $shippingAddressPostalCode,
 'shippingAddressCity' => $shippingAddressCity,
 'shippingAddressState' => $shippingAddressState,
 'shippingAddressCountry' => 'BRA',
 'shippingType' => 1,
 'shippingCost' => '1.00',
 'installmentQuantity' => 1,
 'installmentValue' => '3.00',
 'creditCardHolderName' => 'Chuck Norris',
 'creditCardHolderCPF' => '54793120652',
 'creditCardHolderBirthDate' => '01/01/1990',
 'creditCardHolderAreaCode' => 83,
 'creditCardHolderPhone' => '999999999',
 'billingAddressStreet' => 'Address',
 'billingAddressNumber' => '1234',
 'billingAddressDistrict' => 'Bairro',
 'billingAddressPostalCode' => '58075000',
 'billingAddressCity' => 'João Pessoa',
 'billingAddressState' => 'PB',
 'billingAddressCountry' => 'BRA'
 );

	Note que precisa repetir de acordo com o numero de produtos essa parte

'itemId1' => '0001',
'itemDescription1' => 'PHP Test',
//'itemAmount1' => $numero,
'itemAmount1' => '1.00',

 'itemQuantity1' => 1,

 'itemId2' => '0002',
 'itemDescription2' => 'PHP Test2',
 //'itemAmount2' => $numero,
 'itemAmount2' => '1.00',
 'itemQuantity2' => 1,

	Os produto vem de um array

foreach($product_list_array as $item)

 echo $item->product_price;
 echo $item->product_id;
 echo $item->product_quantity;
 echo $item->product_desc;

}

	Como eu faria para colocar esse **foreach** dentro do **$params=array(...)** junto com as demais informações da compra?