I have to write a redirect rule for the below condition.

www.domain.com/custom.aspx?ATTR=VALUE to www.domain.com/custom?ATTR=VALUE

How can this be achieved using the .htaccess

I have the below set of codes using on the current .htaccess file. Please also suggest where to include your code.

<IfModule mod_rewrite.c>
    Options +FollowSymLinks
    RewriteEngine on
    RewriteRule ^api/rest api.php?type=rest [QSA,L]
    RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
    RewriteCond %{REQUEST_METHOD} ^TRAC[EK]
    RewriteRule .* - [L,R=405]
    RewriteCond %{REQUEST_URI} !^/(media|skin|js)/
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteCond %{REQUEST_FILENAME} !-l
    RewriteRule .* index.php [L]
</IfModule>