Well, I figured out how to make my custom admin products report list with css style. Here is my custom code for those who want to take a look (somo words are in spanish but nothing difficult).
Use it in your wpsc-email_style_purchase_report.php template:
<?php
$purchaseID = ECSE_purchase::get_the_purchase_ID();
global $wpdb;
$cartsql = $wpdb->prepare( "SELECT * FROM <code>" . WPSC_TABLE_CART_CONTENTS . "</code> WHERE <code>purchaseid</code>=". $purchaseID . "", $purchase['id']);
$cart_log = $wpdb->get_results( $cartsql, ARRAY_A );
$j = 0;
// /*
if ( $cart_log != null ) { ?>
<table width="700" border="0" cellspacing="0" cellpadding="0">
<tr>
<th colspan="2" scope="col" align="left" valign="top" style=" padding: 10px 0; color:#004796; font-family:Arial, Helvetica, sans-serif; font-size:13px; line-height:13px; border-bottom: solid 1px #CCC;">Producto</th>
<th width="120" scope="col" align="center" valign="top" style="padding: 10px; color:#004796; font-family:Arial, Helvetica, sans-serif; font-size:13px; line-height:13px; border-bottom: solid 1px #CCC;">Código</th>
<th width="60" scope="col" align="center" valign="top" style="padding: 10px 0; color:#004796; font-family:Arial, Helvetica, sans-serif; font-size:13px; line-height:13px; border-bottom: solid 1px #CCC;">Cant.</th>
<th width="90" scope="col" align="right" valign="top" style="padding: 10px 0 10px 10px; color:#004796; font-family:Arial, Helvetica, sans-serif; font-size:13px; line-height:13px; border-bottom: solid 1px #CCC;">Precio</th>
<th width="90" scope="col" align="right" valign="top" style="padding: 10px; color:#004796; font-family:Arial, Helvetica, sans-serif; font-size:13px; line-height:13px; border-bottom: solid 1px #CCC;">Total</th>
</tr>
<?php
$gsttotal = false;
$endtotal = $total_shipping = 0;
foreach ( (array)$cart_log as $cart_row ) {
$alternate = "";
$j++;
if ( ($j % 2) != 0 )
$alternate = "alt";
$variation_list = '';
$billing_country = !empty($country_data[0]['value']) ? $country_data[0]['value'] : '';
$shipping_country = !empty($country_data[0]['value']) ? $country_data[0]['value'] : '';
$shipping = $cart_row['pnp'];
$total_shipping += $shipping;
$prodID = $cart_row['prodid'];
?>
<tr>
<?php // PRODUCTO ?>
<td width="50" align="left" valign="top" style="padding: 10px 0; border-bottom: dotted 1px #CCC;">
<?php
// levanto la imagen
$item_img = '<img class="product_image" title="'.$cart_row['name'].'" alt="'.$cart_row['name'].'" src="'.get_template_directory_uri().'/timthumb/timthumb.php?src='.wpsc_the_product_image('','', $prodID).'&w=48&h=48&zc=2" style="border:solid 1px #ccc">';
echo $item_img;
?>
</td>
<td width="290" align="left" valign="top" style="padding: 10px 0 10px 10px; color:#004796; font-family:Arial, Helvetica, sans-serif; font-size: 12px; line-height: 15px; border-bottom: dotted 1px #CCC;">
<?php
// nombre de producto
echo apply_filters( 'the_title', $cart_row['name'] );
echo $variation_list;
?>
</td>
<?php // CóDIGO DE PRODUCTO ?>
<td width="120" align="center" valign="top" style="padding: 10px; color:#666; font-family:Arial, Helvetica, sans-serif; font-size: 12px; line-height: 15px; border-bottom: dotted 1px #CCC;">
<?php
$sku = get_post_meta($prodID, '_wpsc_sku' , true);
echo $sku;
?>
</td>
<?php // CANTIDAD ?>
<td width="60" align="center" valign="top" style="padding: 10px 0; color:#666; font-family:Arial, Helvetica, sans-serif; font-size: 12px; line-height: 15px; border-bottom: dotted 1px #CCC;">
<?php
echo $cart_row['quantity'];
?>
</td>
<?php // PRECIO UNITARIO ?>
<td width="90" align="right" valign="top" style="padding: 10px 0 10px 10px; color:#666; font-family:Arial, Helvetica, sans-serif; font-size: 12px; line-height: 15px; border-bottom: dotted 1px #CCC;">
<?php
$price = $cart_row['price'] * $cart_row['quantity'];
echo wpsc_currency_display( $price );
?>
</td>
<?php // PRECIO ITEM TOTAL ?>
<td width="90" align="right" valign="top" style="padding: 10px; color:#666; font-family:Arial, Helvetica, sans-serif; font-size: 12px; line-height: 15px; border-bottom: dotted 1px #CCC;">
<?php
$endtotal += $price;
echo wpsc_currency_display( ($price ), array('display_as_html' => false) );
?>
</td>
</tr>
<?php } ?>
</table>
<?php // TOTAL ?>
<table width="700" border="0" cellpadding="0" cellspacing="0">
<tr>
<td width="360" align="left" style="color:#004796; font-family:Arial, Helvetica, sans-serif; font-size: 14px; line-height:14px; font-weight: bold; border-bottom: dotted 1px #CCC;">TOTAL <small style="color:#666; font-family:Arial, Helvetica, sans-serif; font-size: 12px; font-weight: normal;">(no incluye impuestos)</small></td>
<td width="340" align="right" style="padding: 10px; color:#666; font-family:Arial, Helvetica, sans-serif; font-size: 14px; line-height:14px; border-bottom: dotted 1px #CCC; font-weight: bold;">
<?php
$endtotal += $purchase['wpec_taxes_total'];
echo wpsc_currency_display( $endtotal , array('display_as_html' => false) );
?>
</td>
</tr>
</table>
<?php } ?>