copy /app/code/core/Mage/Checkout/Model/Session.php

/app/code/local/Mage/Checkout/Model/Session.php

$this->_quote = $quote;

$sha = $quote->getShippingAddress();
if (!$sha->getCountry()) {
$country = Mage::getStoreConfig('shipping/origin/country_id');
$state = Mage::getStoreConfig('shipping/origin/region_id');
$postcode = Mage::getStoreConfig('shipping/origin/postcode');
$quote->getShippingAddress()
->setCountryId($country)
->setRegionId($state)
->setPostcode($postcode)
->setCollectShippingRates(true);
$quote->save();
}

/app/design/frontend/base/default/checkout/cart/shipping.phtml

/app/design/frontend/default/YOURTEMPLATE/checkout/cart/shipping.phtml

<form id="co-shipping-method-form" action="<?php echo $this->getUrl('checkout/cart/estimateUpdatePost') ?>">
        <dl class="sp-methods">
            <?php foreach ($_shippingRateGroups as $code => $_rates): ?>
                <dt><?php echo $this->escapeHtml($this->getCarrierName($code)) ?></dt>
                <dd>
                    <ul>
                    <?php foreach ($_rates as $_rate): ?>
                        <li<?php if ($_rate->getErrorMessage()) echo ' class="error-msg"';?>>
                           <?php if ($_rate->getErrorMessage()): ?>
                                <?php echo $this->escapeHtml($_rate->getErrorMessage()) ?>
                           <?php else: ?>
                                <input name="estimate_method" type="radio" value="<?php echo $this->escapeHtml($_rate->getCode()) ?>" id="s_method_<?php echo $_rate->getCode() ?>"<?php if($_rate->getCode()===$this->getAddressShippingMethod()) echo ' checked="checked"' ?> class="radio" />
                                <label for="s_method_<?php echo $_rate->getCode() ?>"><?php echo $this->escapeHtml($_rate->getMethodTitle()) ?>
                                <?php $_excl = $this->getShippingPrice($_rate->getPrice(), $this->helper('tax')->displayShippingPriceIncludingTax()); ?>
                                <?php $_incl = $this->getShippingPrice($_rate->getPrice(), true); ?>
                                <?php echo $_excl; ?>
                                <?php if ($this->helper('tax')->displayShippingBothPrices() && $_incl != $_excl): ?>
                                    (<?php echo $this->__('Incl. Tax'); ?> <?php echo $_incl; ?>)
                                <?php endif; ?>
                                </label>
                           <?php endif ?>
                        </li>
                    <?php endforeach; ?>
                    </ul>
                </dd>
            <?php endforeach; ?>
        </dl>
        <div class="buttons-set">
            <button type="submit" title="<?php echo $this->__('Update Total') ?>" class="button" name="do" value="<?php echo $this->__('Update Total') ?>"><span><span><?php echo $this->__('Update Total') ?></span></span></button>
        </div>
    </form>