Can a webhook be created that pulls data from another Marketo record?

We are creating new lead records that are referred from other leads in Marketo/SFDC.  We capture the referrer's SFDC ID in a field on the new lead record from the query parameter in the link the referrer has to our website.  We want to send an email to the new lead that includes the referrer's name and email address.  Is it possible to create a webhook thta would use the Marketo SOAP API to update fields in the referred lead's record with the values from the referrer's lead record and  if so, what should be in the various sections of the webhook? 

Below is the configuration of the webhook I created to do this, but it failed with the error string 'connect() timed out!'.  Any ideas where i am going wrong?

Request Type:	http_post
url:	https://[our org ID].mktoapi.com/soap/mktows/2_6
payload:	<?xml version="1.0" encoding="UTF-8"?> <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns1="http://www.marketo.com/mktows/"> <SOAP-ENV:Header> <ns1:AuthenticationHeader> <mktowsUserId>[our User ID]</mktowsUserId> <requestSignature>[our Encryption Key]</requestSignature> <requestTimestamp>{{system.dateTime:default=}}</requestTimestamp> </ns1:AuthenticationHeader> </SOAP-ENV:Header> <SOAP-ENV:Body> <ns1:paramsGetLead> <leadKey> <keyType>SFDCACCOUNTID</keyType> <keyValue>{{lead.eReferrer:default=edit me}}</keyValue> </leadKey> </ns1:paramsGetLead> </SOAP-ENV:Body> </SOAP-ENV:Envelope>

Request Token Encoding:  URL

Response Type: XML