Unix services rlogin/rsh not working through ICS

I need to access to remote UNIX servers using rsh/rlogin protocols via
ICS on Windows XP.
I'm accessing the remote servers via CISCO VPN on Windows XP on which I
have activated ICS
My client systems are behind Windows XP on a local network
I've set a route on my client systems to use the Windows XP machine as
router for the remote servers IP address range.

This config works very well for standard services like telnet or ftp.
But it does not work for rsh/rlogin services because they require that
the source port is in the range 512-1024.
The client software (rsh or rcp) uses port 1023 to establish the
connection but ICS converts it to a dynamic number > 1024. When the
connection arrives on the remote servers, they refuse the connection.

Does anyone know how I can configure ICS so that it does not change the
source port if it falls < 1024?

I've tried to configure some services in ICS but that doesn't make a
difference (logical as these are used for inbound connections)