In your template (towards the top) find this:
<$BlogMetaData$>Then place the following code right after it.
<link rel="icon" href="FAVICON URL" type="favicon" />
<link rel="shortcut icon" href="FAVICON URL" type="favicon" />
If you have the new blogger template (formerly known as blogger beta) there is a fix for them, also.
Pretty easy. I really love my favicon, and I'm very upset with Blogger for attempting to do away with it. Shame, shame on you Blogger!