Hi Mark,
I agree with Gyorgy. It will likely do more harm than good to change the underscores to hyphens because then links to those pages will have to go through a redirect.
However, if you are set on making this change here's how you can do it using the .htaccess file. Hope this helps!
`RewriteCond %{REQUEST_FILENAME} !\.(gif|png|jpg|jpeg|bmp)$ [NC]`<code>rewriteRule ^([^]*)([^]*)([^]*)(.*)$ http://www.payscout.com/$1-$2-$3-$4 [R=301,L]
rewriteRule ^([^]*)([^]*)(.*)$ http://www.payscout.com/$1-$2-$3 [R=301,L]
rewriteRule ^([^]*)(.*)$ http://www.payscout.com/$1-$2 [R=301,L]</code>
