Thanks, unfortunately it didn't work.

<?xml version="1.0" encoding="UTF-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" x
+mlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/" xmlns:xsd="h
+ttp://www.w3.org/2001/XMLSchema" soap:encodingStyle="http://schemas.x
+mlsoap.org/soap/encoding/" xmlns:soap="http://schemas.xmlsoap.org/soa
+p/envelope/" xmlns:ssl="http://ssl.ws.epki.comodo.com/">
<soap:Body><getWebServiceInfo xsi:nil="true" /></soap:Body></soap:Enve
+lope>

SOAP::Transport::HTTP::Client::send_receive: HTTP::Response=HASH(0x13a
+c35d0)
SOAP::Transport::HTTP::Client::send_receive: HTTP/1.1 500 Internal Ser
+ver Error
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I got this to work, is this too much of a hack? Update: I am quite sure it is the correct thing to do. See below.

$soap->ns("http://ssl.ws.epki.comodo.com/", 'ssl');
my $method = SOAP::Data->name('ssl:getWebServiceInfo');
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POST https://certificatemanager.comodo.com:443/ws/EPKIManagerSSL HTTP/
+1.1
...
SOAPAction: "http://ssl.ws.epki.comodo.com/#getWebServiceInfo"

<?xml version="1.0" encoding="UTF-8"?><soap:Envelope xmlns:xsi="http:/
+/www.w3.org/2001/XMLSchema-instance" xmlns:soapenc="http://schemas.xm
+lsoap.org/soap/encoding/" xmlns:xsd="http://www.w3.org/2001/XMLSchema
+" soap:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmln
+s:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ssl="http://
+ssl.ws.epki.comodo.com/"><soap:Body><ssl:getWebServiceInfo xsi:nil="t
+rue" /></soap:Body></soap:Envelope>

HTTP/1.1 200 OK
Connection: close
Date: Thu, 11 Aug 2011 13:28:38 GMT
Server: Apache-Coyote/1.1
Content-Type: text/xml;charset=utf-8
...

<?xml version="1.0" ?><S:Envelope xmlns:S="http://schemas.xmlsoap.org/
+soap/envelope/"><S:Body><ns2:getWebServiceInfoResponse xmlns:ns2="htt
+p://ssl.ws.epki.comodo.com/"><return>Comodo Certificate Manager. SSL 
+Web Service. Version 1.1.</return></ns2:getWebServiceInfoResponse></S
+:Body></S:Envelope>
[download]

That's great. It works for me too. Thanks for helping out!