Setting custom summary as required for blogs


I'm looking at making the "custom summary" in the blog creation form default and required to have some sort of input before a blog post can be created.

I have amended the code as so to make it default for the blog post create/edit widget:

#if ($core_v2_blogConfiguration.IsCrossPostingEnabled && $blog.EnableCrossPostingDefault)
	<li class="field-item post-crossposting">
		<span class="field-item-input">
			<input type="checkbox" id="$core_v2_widget.UniqueId('isCrossPostingEnabled')"#if(!$post || $post.EnableCrossPosting) checked="checked"#end />
			<label for="$core_v2_widget.UniqueId('isCrossPostingEnabled')">$core_v2_language.GetResource('Post_CrossPosting')</label>

Is there a simple way to make this field required to have input through classes or another value I can change or is it more complex then that.