Magento – Pass custom attribute from product listing to cart page

The quote items are kept in the db.
Since there are not columns to support your package and tint attributes the values you set to the item are not persistent.

So setting

$item->setPackage('Silver'); // these values are depends upon customers selection
$item->setTint('Green');

Makes these values available only in the current request.
When the page is realoaded, the quote items are retrieved from the db and they don't have package and tint.

You should add 2 more columns in the table sales_flat_quote_item that will hold these values.
Clear the cache when your are done.
To be able to access these values from the order items you need to do the same for the table sales_flat_order_item.
Add 2 columns and then tell magento that when it creates an order item from a quote item it should copy these fields also.

You can do this via the fieldsets from config.xml.

In one of your custom modules, inside the config.xml add this inside the <global> tag.

<fieldsets>
    <sales_convert_quote_item><!-- when converting a quote item -->
        <package> <!-- copy the package field ...-->
             <to_order_item>*</to_order_item> <!-- .. to the order item -->
        </package>
        <tint>
             <to_order_item>*</to_order_item>
        </tint>
    </sales_convert_quote_item>
</fieldsets>

Additional...if you want these values to be available on the invoice items, shipment items and creditmemo items, you need to add the same 2 columns in the tables sales_flat_invoice_item, sales_flat_shipment_item and sales_flat_creditmemo_item.

And inside the same <fieldsets> xml node as above add this:

<sales_convert_order_item>
    <package>
        <to_quote_item>*</to_quote_item>
        <to_invoice_item>*</to_invoice_item>
        <to_shipment_item>*</to_shipment_item>
        <to_cm_item>*</to_cm_item>
    </package>
    <tint>
        <to_quote_item>*</to_quote_item>
        <to_invoice_item>*</to_invoice_item>
        <to_shipment_item>*</to_shipment_item>
        <to_cm_item>*</to_cm_item>
    </tint>
</sales_convert_order_item>

In .../template/catalog/product/list.phtml, you'll see $this->getAddToCartUrl($_product). This generates the URL to add to cart. You can create a custom function that places the product URL instead in your case. Check it out.

• Takes in $_product as its argument
• Checks if $_product has any custom options. See below
• Returns $this->getAddToCartUrl(...) if no custom options. Returns $this->getProductUrl(...) if at least one custom option is present.

To check if a product has any custom attributes at all..

$options = $product->getOptions();
if ($options) {
    return true; // has custom options
} else {
    return false; // no custom options
}