Alright, I'm running a regular PSP with 3.52 M33-4.
I just tried using iR Shell for the first time today. I downloaded the original 3.6 version and installed it, then overwrote the files with the 3.61 update for newer firmwares. So I think everything is in order.
My problem is with USBHost. I pretty much followed the instructions exactly. I unzipped the drivers to my C Drive, then I ran usbhostfs.exe. Then I toggled USBHost in the iR Shell and it said it couldn't connect. But it did bring up the New Hardware thing. So I told it to search for drivers in the Drivers folder from usbhost, and it found/installed them without a problem. It said that Type B thing while installing (which I've heard is the right thing <_<) and didn't give me errors or anything. So now I'm guessing I'm ready to actually use the USBHost feature. The problem is, it still pops up saying "Cannot connect to USBHost" or whatever when I try to use it. As far as I know, I haven't done anything wrong, but it just won't connect.
I'm running Windows XP SP2, and I've disabled Windows/Any other firewall I had running. Still no luck.
 One thing I should mention. I moved the location of the driver on my PC. I originally unzipped it to some folder in My Documents, but then I heard that it can only find files in the directory above it. So after I installed the driver using the Found New Hardware pop-up, I moved the drivers to the root C drive and deleted the one in my documents. Whenever I try and connect, it doesn't bring up the "Found New Hardware" thing again, so I'm assuming it knows where the drivers went. Even with the driver in the original location, it still wouldn't connect though.