I have to say that I continue to be frustrated with finding out how to do things in Windows 8. Here's another one and it's recorded so it might help someone else. I've also documented what I tried so that if anyone from the product group ever reads this, they'll understand how I searched for it and might try to make it easier.
I wanted to add a network loopback adapter, to have a fixed IP address to work with when using an "internal" network with Hyper-V. (The fact that I even need to do this is also painful. I don't know why Hyper-V can't make it easy to work with host system folders, etc. as easily as I can with VirtualPC, VirtualBox, etc. but that's a topic for another day).
In the end, what I needed was a known IP address on the same network that my guest OS was using, via the internal network (which allows connectivity from the host OS to/from guest OS's).
I started by looking in the network adapters areas but there is no "add" functionality there. Realising that this was likely to be another unexpected challenge, I resorted to searching for info on doing this. I found KB article 2777200 entitled "Installing the Microsoft Loopback Adapter in Windows 8 and Windows Server 2012". Aha, I thought that's what I'd need. It describes the symptom as "You are trying to install the Microsoft Loopback Adapter, but are unable to find it." and that certainly sounded like me. There's a certain irony in documenting that something's hard to find instead of making it easier to find. Anyway, you'd hope that in that article, they'd then provide a step by step example of how to do it, but what they supply is this:
The Microsoft Loopback Adapter was renamed in Windows 8 and Windows Server 2012. The new name is "Microsoft KM-TEST Loopback Adapter". When using the Add Hardware Wizard to manually add a network adapter, choose Manufacturer "Microsoft" and choose network adapter "Microsoft KM-TEST Loopback Adapter".
The trick with this of course is finding the "Add Hardware Wizard". In Control Panel -> Hardware and Sound, there are options to "Add a device" and for "Device Manager". I tried the "Add a device" wizard (seemed logical to me) but after that wizard tries it's best, it just tells you that there isn't any hardware that it thinks it needs to install. It offers a link for when you can't find what you're looking for, but that leads to a generic help page that tells you how to do things like turning on your printer.
In Device Manager, I checked the options in the program menus, and nothing useful was present. I even tried right-clicking "Network adapters", hoping that would lead to an option to add one, also to no avail.
So back to the search engine I went, to try to find out where the "Add Hardware Wizard" is. Turns out I was in the right place in Device Manager, but I needed to right-click the computer's name, and choose "Add Legacy Hardware". No doubt that hasn't changed location lately but it's a while since I needed to add one so I'd forgotten. Regardless, I'm left wondering why it couldn't be in the menu as well.
Anyway, for a step by step list, you need to do the following:
1. From Control Panel, select "Device Manager" under the "Devices and Printers" section of the "Hardware and Sound" tab.
2. Right-click the name of the computer at the top of the tree, and choose "Add Legacy Hardware".
3. In the "Welcome to the Add Hardware Wizard" window, click Next.
4. In the "The wizard can help you install other hardware" window, choose "Install the hardware that I manually select from a list" option and click Next.
5. In the "The wizard did not find any new hardware on your computer" window, click Next.
6. In the "From the list below, select the type of hardware you are installing" window, select "Network Adapters" from the list, and click Next.
7. In the "Select Network Adapter" window, from the Manufacturer list, choose Microsoft, then in the Network Adapter window, choose "Microsoft KM-TEST Loopback Adapter", then click Next.
8. In the "The wizard is ready to install your hardware" window, click Next.
9. In the "Completing the Add Hardware Wizard" window, click Finish.
Then you need to continue to set the IP address, etc.
10. Back in Control Panel, select the "Network and Internet" tab, click "View Network Status and Tasks".
11. In the "View your basic network information and set up connections" window, click "Change adapter settings".
12. Right-click the new adapter that has been added (find it in the list by checking the device name of "Microsoft KM-TEST Loopback Adapter"), and click Properties.