HTTPのレスポンスヘッダもしくはMETAタグ。
On a per-site basis, add a custom HTTP header
X-UA-Compatible: IE=EmulateIE7
On a per-page basis, add a special HTML tag to each document, right after the <head> tag
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7" />