I wrestled with this all Xmas day

yes, I'm a Windows user too!
Here's what I did - might help someone.
Say you have four drives, and you want to install Fedora into a smallish partition on Drive 1, have the rest of Drive 1 for storage using Greyhole, and the other three drives all for storage.
Allow default install of "replace existing Linux installation", but say you want to work with the partitions. Only allow Drive 1 to be part of the installation - untick the other drives (otherwise I think all the drives we become one huge LVM drive, and we want separate partitions to be able to use Greyhole properly for redundancy).
By default that will create a separate "boot" partition of say 200MB, a / (root) partition and a swap partition (these will will take up all of Drive 1). But if like me you have a large drive 1, you don't want that - especially after having been warned to not use / with Greyhole - so edit / to knock it down in size, say to 10000MB. Now create a "landing strip" where you will have Amahi put files temporarily before Greyhole moves them to your storage partitions - create a *new* partition, perhaps /home (you can pick it from the dropdown) and make it large enough that it can take all the files you want to move there temporarily. I might put say 150GB there in one go before it empties again, so I went with 200000MB to be safe, but obviously your mileage will vary. Now, do another new partition, BUT *type in* the name "/storage" and let it use all the rest of the free space on Drive 1. This will take some of our data after it's been moved by Greyhole, along with the other three storage drives.
After the Fedora and then Amahi install, you will need to install gparted, format the other 3 drives (perhaps to ext3 or 4) and follow the Amahi wiki instructions to mount them. Then, in the dashboard, change the location of your shares from var/hda/files/whatever to use home/hda/files/whatever as the location. Next, enable Greyhole, add /storage, Drive2, D3 and D4 to the pool, then set your shares to use the pool.
Hope that makes sense
