Hey, that's my setup you're talking about there! Here's the deal regarding the 4560 backhoe on the Grand L-10 series... it requires getting a different ROPS with a slightly different bolt pattern designed to line up with the backhoe subframe. The dealer did that on my 4610 when I added the 4560 BH.
The alternate ROPS is about 6" taller than the original one, and I'm speculating that the increase in height was necessary for safety reasons due to the size/weight of the backhoe.
Once you get the right ROPS installed, the backhoe subframe installation is pretty straightforward. It is a pretty slick piece of engineering - at least to my simple mind - with the backhoe tucked in close to the rear axle, a true 4 point subframe installation, and yet the 3 point works just the same as without the BH.
In actual use, adding/removing the backhoe is a bit more work than changing 3pt implements, but with a little practice, it's not a major deal either. You do have to remove the 3pt links, but they come off with a couple of bolts, and you have to add a stabilizer pin for the pto pump, using one bolt.
It's a strong backhoe and will do some serious digging. Attached is a photo of mine clearing about an acre of pine stumps a while back, one of many projects the 4610/4560 has done in 8 trouble-free years.
Judging the sparse replies here, I guess there aren't many of these backhoes around. You did get me to re-activate my TBN account so I could pass this information on... I read the forums regularly, but have not posted for some time.
Good luck with the installation. By the way, I do have the original manuals which have installation instructions. If a dealer can't help you with this, send me a private message.