Example config to add a new Magento page type and disable one_column form being default

config.xml

<?xml version="1.0"?>
<config>
    ...
    <global>
        <page>
            <layouts>
                <vendor_page module="page">
                    <label>Vendor Default</label>
                    <template>page/html.phtml</template>
                    <layout_handle>vendor_page</layout_handle>
                    <is_default>1</is_default>
                </vendor_page>
                <one_column>
                    <is_default>0</is_default>
                </one_column>
            </layouts>
        </page>
    </global>
</config>