I have a custom module, whose content I need to show on Order Details page.
Not under any new tab or something but just above the "Order Totals" div.
How do I accomplish this without modifying any core files?
Add layout file in yourmagento/app/design/adminhtml/default/default/layout/yourmodule.xml
Add below content in that:
<adminhtml_sales_order_view>
<reference name="order_tab_info">
<action method="setTemplate">
<template>yourmodule/sales/order/view/tab/info.phtml</template>
</action>
<!-- Add your block to display in above order total block -->
</reference>
</adminhtml_sales_order_view>
Copy default info.phtml file from app/design/adminhtml/default/default/template/sales/order/view/tab/info.phtml to app/design/adminhtml/default/default/template/yourmodule/sales/order/view/tab/info.phtml
Add your content in info.phtml as per your need above order total div.
To add the contents to the Order Information section (First block on the admin order page), inside app/design/adminhtml/default/default/layout/yourmodule.xml add below:
<adminhtml_sales_order_view>
<reference name="order_info">
<action method="setTemplate">
<template>yourmodule/sales/order/view/info.phtml</template>
</action>
</reference>
</adminhtml_sales_order_view>
Now you can copy:
app/design/adminhtml/default/default/template/sales/order/view/info.phtml
to
app/design/adminhtml/default/default/template/yourmodule/sales/order/view/info.phtml
Now you can add your stuff to the info.phtml inside your module, without change the core files.