I think they offered that to me as well, the sliders fit the seats but not the Landy!
Basically you bolt the subframe/adaptor plate into the seat via 4 bolts, then you bolt the sliders to the subframe and the sliders to the LR seatbox.
Its easy to do, from you pics you have original seats fitted. So pop out n have a look, there will be 3 Phillips heads running down either side, lather these in gallons of Plus Gas. I had to drill out the majority of mine, then hammer the captive nuts out and replace, some of the captives where fine though.
Then get some replacement nuts and bolts M8 high tensile are the ones you want. I used nice allen key/socket heads on mine with some stainless washers.