Your while loop only executes whenever File::Tail finds a new line appended to the file you're watching. So you could do this (reformatted a bit for readability):

my $file=File::Tail->new( name        => $name,
                          maxinterval => 1,
                          adjustafter => 1);

while (defined(my $line=$file->read)) {
    my($logindate,$loginuser,$logoutdate,$logoutuser,$count);
    if($line =~ /INFO\s\s(\d+)(\d+)-(\d+)-(\d+)\s(\d+):(\d+):(\d+),(\d
++)\s\[(.*)\]\s\((.*)\) - validateLogin\((.*)\)/){
        $logindate = "$1$2-$3-$4 $5:$6:$7,$8";
        $loginuser = "$11";
        if(($logging)&&($debug)){
            &writelog(1,"DEBUG: Tail Event Login found user date strin
+g = $logindate user = $loginuser");
        }
    }
    if (my $inp= ReadLine (-1)) {
        print "Got this command: $inp";
    }
}
[download]

And this would work, but the loop would only check for input anytime a line is added to the log, and block until then. If you don't want to do that you'll need to use File::Tail->select instead of read, take a look at the example that comes with File::Tail and the perldoc on that.