Yes, there is a way. Thank you for reminding me how to do it.

These are set at 64x64, but you can use whatever dimensions you need.
In the usercp.php file, replace this:
Code:
$avatarimage='<img src="'.$avatarurl.'" border="0" alt="Search for all posts by '.$username.'">';
With this:
Code:
$avatarimage='<img src="'.$avatarurl.'" border="0" alt="Search for all posts by '.$username.'" width="64" height="64">';
And replace this:
Code:
$avatarimage='<img src="'.$avatarurl.'" border="0" style="filter:alpha(opacity=50)" alt="Search for all posts by '.$username.'">';
With this:
Code:
$avatarimage='<img src="'.$avatarurl.'" border="0" style="filter:alpha(opacity=50)" alt="Search for all posts by '.$username.'" width="64" height="64">';