first write this code between head tag and try it
document.getElementById('myHeader').style.filter="glow(strength=" + i + ")"
else if (window.interval)
and write this code after body tag in your html code
I would steer clear of blinking text if it causes seizures but if you must have blinking text I would put a warning up for people with seizures so we will navigate elsewhere to prevent seizures.
This is a greatly exaggerated threat, as a little research will quickly show:
"As far as I'm aware, there has never been a reported case of photosensitive epilepsy caused by web content ..." http://juicystudio.com/article/photosensitive-epilepsy.php#andtheweb
The fact is that blinking is both distracting and annoying. Why would you want to distract and annoy your visitors?
Blinking is kinda' like Flash:just because you can doesn't mean you should.
However unless your page is a "myspace" page I would follow everyone's advice and stay away from blinking objects. If you seriously cant resist the blinking objects then find some advertisments to place on your page that use .gif banner ads. at least you'll have a chance of making some money out of it.