Latest visibilities.More locations dropping below 1 mile.twitpic.com/cwfvxl
— Daryl Ritchison (@DarylRitchison) June 10, 2013
Windows Live Writer  has a Source tab on the lower left hand side of the application:
Typically, what I like to do is go to twitter.com and click the # Discover command on the top navigation pane:
Click on More, then click Embed Tweet.
Embed Tweet command
Then just copy the code and paste it into Windows Live Writer after you click on the Source tab.
Source tab in Windows Live Writer
Relevant part of code [text] highlighted. I’ll typically paste this in before there’s any code, right after creating a new post. The Source tab will be blank until you start typing or paste in code.
When you click on the Edit tab to return to WYSIWYG mode, the tweet will appear as it does at the top of this post.
WYSIWYG: What you see is what you get. In web authoring and publishing it’s when you edit something from a graphical user interface [GUI]. As opposed to editing the raw code [HTML] in the Source tab.