Being a 04 your seat is probably the same as my VY sedan so will need later model vy or vz seats, so the seat will bolt straight in,
wiring is 3 wire hookup you memory, earth and power for the seat, and another wire for the seatbelt warning light/beep(early vy don't have the addition wire)
Worst case is you might be able to get a pair of seats from any vy, vz with the adjustment and remove the foam and trim from yours and refit them to the new frames, I done this to my vy Berlina and fitted full 8 way electric memory seat frames from a vy Calais , reusing the berlina trim, as mine are in very good condition
I have a vy workshop manual with the assembly instructions if you need some info, quite easy to do, you might only need to remove the seat base and swap it over not completely disassemble back of the seat, seats come apart quite easy
Just need to know what seats you currently have, so I can send you the correct info, also a email address