Looking at this
Brochure not much help. My cabinets were open to the over head side speakers so just had to remove the existing and place in the new ones.
While I was in there was able to swap out the rear speaker control wire leads off radio so Kitchen speakers were move to rear bedroom speaker leads, off the rear fade control leads so I could control all front speakers from radio.
I was able to put 6x9 speakers in that space.
When I put in the DVD 5.1 system I can play FM through the new speakers of the DVD system because its wired off the small inverter 120 outlet its wired to for power while traveling, best of both worlds.
Can see setup in
QT's 1 & 2.
If you can see the speakers from a cabinet or remove a plywood panel in cabinet to side of speaker space maybe done.
If you could post some pictures maybe able to help more.