hola,
You'll just have to change these lines :
if(!empty($this->links->previous))
echo "<a title='".JText :: _('PREVIOUS_PRODUCT')."' href='".$this->links->previous."'><span class='hikashop_previous_product'></span></a>";
if(!empty($this->links->next))
echo "<a title='".JText :: _('NEXT_PRODUCT')."' href='".$this->links->next."'><span class='hikashop_next_product'></span></a>";
By :
if(!empty($this->links->previous))
echo "<a title='".JText :: _('PREVIOUS_PRODUCT')."' href='".$this->links->previous."'><span class='hikashop_previous_product'></span></a><span class='hikashop_previous_product_test'>".JText :: _('HIKA_PREVIOUS')."</span>";
if(!empty($this->links->next))
echo "<a title='".JText :: _('NEXT_PRODUCT')."' href='".$this->links->next."'><span class='hikashop_next_product'></span></a><span class='hikashop_next_product_text'>".JText :: _('HIKA_NEXT')."</span>";
And add use some CSS code like :
.hikashop_next_product_text {
float: right;
width: 35px;
height: 35px;
}
.hikashop_previous_product_test {
float: left;
width: 35px;
height: 35px;
}