I think most spell checkers are add on's. I dont use IE but have found this that might be of help to you.
Just do a search for speckie.
Speckie is a free, add-on for IE9 that provides a real-time spell-checker that looks just like the one available in Chrome or Firefox. It underlines misspelled words you type in a form in your browser, just like Microsoft Word does.
There are other options for adding spell-checking to IE9, such as ieSpell. However, there are a few features unique to Speckie. It is the first and only real-time, dedicated spell checking solution for IE. Speckie can use one or more dictionaries simultaneously (it supports more than 30 different languages) and it is the only spell checker that works with the 64-bit version of IE. You can run Speckie in Internet Explorer 6, 7, 8, or 9 on Windows XP, Vista, and 7 (32 and 64 bit).
NOTE: IE doesn’t work with browser windows that are pinned to the start menu or taskbar as web apps. This is by design. IE does not load toolbars or extensions like Speckie on pinned sites for security reasons.
Installing Speckie is simple. Simply double-click on the .exe file you downloaded (see download link at the end of this article) and follow the instructions in the setup wizard, clicking Yes on the User Account Control dialog box, if needed.
