Assuming I understand the problem correctly: your client is connected to server A; you want to get the info the client has entered into forms SECURELY to HTTPS server B, and redirect the client to server B.

Here's how I might do it (a bit Rube-Goldberg-y, but ...):

1. POST the info via LWP, over HTTPS (requires some tricksyness) to a CGI running on server B.
2. CGI on B stores the info, creates a session ID, then passes the session ID back (via HTTPS) to server A.
3. Server A sets a cookie on the client, or passes back the session ID via the URL in the redirect, which is of course an HTTPS url.

Unless, of course, there's some other way of safely exchanging info between A and B (like, say, an RDBMS to which they can both securely connect?)...

Philosophy can be made out of anything. Or less -- Jerry A. Fodor