In a broad sense what you are trying to do isn't possible. You can't just designate drives or portions of drives as part of a LVM and have that work. It would be possible if you had enough space on the machine and drives that weren't going to be part of the LVM, to transfer all the data from drives that were going to be part of the LVM to non-LVM drives, then create the LVM, and copy the data back. Doing so would not be in the least bit trivial however. It would require much comfort with linux CLI (command line interface), and knowledge of how to mount/unmount disks and partitions.
You would probably find it much easier to take the machine down, and rebuild it from scratch. Not knowing what is on the machine I can't give specifics, but I would suggest copying off the important data and configuration files, then rebuilding with LVM, and tossing the old configs back on.
I would guess you can't find documentation on what you are trying to do because it isn't done too often, and the directions to do what you are looking for would read more like script than human directions.
If you want to post more on the partitions and disks (sizes, mountpoints etc) and what is installed, someone may have instructions for you. Again, without massive space and enough space to hold all your data on drives that aren't going to be part of the LVM, I don't think this will work without rebuilding.
You may have some luck with these search results from google.com/linux http://www.google.com/linux?hl=en&lr...VM&btnG=Search
Actually, this thread seems to be dealing with exactly what you have, but on a home system rather than a hardware RAID server. That won't make any difference, but it does seem to be possible: