How to modify this Irule with HTTP_REQUEST replacing CLIENT_ACCEPTED

You should still be able to use the TCP::local_port command in the HTTP_REQUEST event, so:

when HTTP_REQUEST {
    switch [TCP::local_port] {
        "5000"  {
            pool example_ems
        }
        "5005"  {
            pool example_ems
        }
        "5100"  {
            pool example_webvis
        }
        "5105"  {
            pool example_webvis
        }
        "5110"  {
            pool example_recall
        }
        "5115"  {
            pool example_recall
        }
        "5200"  {   
            pool example_recon
        }
        "5205"  {   
            pool example_recon
        }
        "5400"  {   
            pool example_hub
        }
        "5405"  {   
            pool example_hub
        }
        default {
            HTTP::redirect "https://[HTTP::host][HTTP::uri]"
        }
    }        
}

You could also save yourself the hassle of a complex iRule by using a data group:

when HTTP_REQUEST {    
    if { [class match [TCP::local_port] equals my_datagroup] } {        
        pool [class match -value [TCP::local_port] equals my_datagroup]            
    } else {        
        HTTP::redirect "https://[HTTP::host][HTTP::uri]"            
    }        
}    

where "my_datagroup" is a string-based data group:

5000 := example_ems
5005 := example_ems
5100 := example_webvis
5105 := example_webvis
5110 := example_recall
5115 := example_recall
5200 := example_recon
5205 := example_recon
5400 := example_hub