If you don't run that server yourself, then you'll have to check with the hoster's policies in any case, before you continue. This restriction is probably there for a reason. If in doubt, ask them first.
That being said, you can just wrap the call to the perl interpreter somehow, so that the sendmail process doesn't notice it.
Make sure you have the line "#!/usr/bin/perl" (without the quote) as the very first line of your script and give the file execute permissions so that the sendmail process can run it. Then you can have the .forward file just call the script directly, without mentioning perl. Of course, if sendmail is smart, then it will catch this trick and balk anyway.
Alternatively, create a file emailcapture.sh, with the following contents:
exec /usr/bin/perl /home/virtual/talklist/home/httpd/cgi-bin/arplus/emailcapture.pl
(unwrap the second line if necessary) give it execute permissions, and then just call this file from .forward.
The net effect of either method should be identical to what you tried at first, unless the current sendmail versions have really sophisticated security checks built in.
Note that you *are* potentially opening security holes by running perl scripts from .forward, so you better make sure your script is next to trivial and you understand *completely* what it does.