As DreamHost runs CGI scripts as your user (via suexec) you can place the script in any directory you want - just set it, and the directory it is in, to 755 permissions.
that depends on where you put the script! .
if you put the script in home/youruser/youdomainname.tld/scripts then the path to call the script would be :
home/youruser/youdomainname.tld/scripts/nameofscript.pl (or cgi, etc.)
the url of the script is likely to be "http://yourdomainname.tld/scripts/nameofscript.pl"
I have not looked at the script in a while, but probably only the shebang line (first line of the script). The path to perl on Dreamhost is: