Hello,
The following parameter will redirect any request from HTTP to HTTPS:
icm/HTTP/redirect_0 = PREFIX=/, FROMPROT=HTTP, PROT=HTTPS, HOST=web_disp_server.domain.com
(notice it should be all in one line)
If you want to switch only for a specific request (e.g., login) you can add "FROM=...." to the parameter.
Then, you would have to create another redirect parameter to switch back to HTTP.
It could be tricky and could require a lot of effort to "fine tune" all your redirects if you really need to create the "switch back" scenarios.
I would recommend to force the switch to HTTPS and keep all traffic as HTTPS...
Regards,
Isaías