here the solution

I installed Rational Application Developer 7.5 then WebSphere Portal 6.1 in administration mode
and after the install I launched : ConfigEngine.bat enable-develop-mode-startup-performance -Dpassword=********

In RAD I see the proper runtimes : (rational > server > runtime environments)
WebSphere Portal v6.0 stub
WebSphere Portal v6.1

I added a new server : WebSphere Portal v6.1 server at localhost (server runtime environment : WebSphere Portal v6.1)

in RAD, when you create a new server specify the good RMI and SOAP ports
and don’t forget to ckeck the security section

the ports are described there :
C:\IBM\WebSphere\wp_profile\ConfigEngine\properties\wkplc.properties
la.providerURL=corbaloc:iiop:localhost:10031
WPS_SOAP_PORT=10035

you can also see them when starting the console
C:\IBM\WebSphere\AppServer\bin>startServer.bat server1
log into the console https://localhost:10005/ibm/console/logon.jsp
and go to servers > Application servers > WebSphere_Portal
click on ports and you’ll see

Port Name Port
BOOTSTRAP_ADDRESS 10033
SOAP_CONNECTOR_ADDRESS 10035
SAS_SSL_SERVERAUTH_LISTENER_ADDRESS 10034
CSIV2_SSL_SERVERAUTH_LISTENER_ADDRESS 10027
CSIV2_SSL_MUTUALAUTH_LISTENER_ADDRESS 10039
WC_adminhost 10029
WC_defaulthost 10042
DCS_UNICAST_ADDRESS 10031
WC_adminhost_secure 10043
WC_defaulthost_secure 10037
SIP_DEFAULTHOST 10041
SIP_DEFAULTHOST_SECURE 10038
SIB_ENDPOINT_ADDRESS 10028
SIB_ENDPOINT_SECURE_ADDRESS 10040
SIB_MQ_ENDPOINT_ADDRESS 10032
SIB_MQ_ENDPOINT_SECURE_ADDRESS 10030
ORB_LISTENER_ADDRESS 10036

regards.
Ben

some people suggest to install portal using IBM Installation Manager : http://www.ibm.com/developerworks/forums/thread.jspa?threadID=238462&tstart=0
but they don’t say how.

If you have any idea….
regards.