No clue how to manually operate the bedroom slide on a 290. Thankfully I have not had to do that one.
For what its worth in getting my slide problem fixed under warranty (break in the ground wire somewhere between the grounding bar and the switch which required pulling a new ground wire to the switch), I asked for the two holes in the side to be drilled into the unit to operate the slides manually. This is how the owners manual states to operate them manually. I said they were missing and must have been forgotten in the build.
My request was denied and I was given written instructions on how to manually work the rear slides on my unit and told they were not missed in the build.
Its not mentioned how to do that anywhere in writing that I could find.