take a sawsall to it. ..depending on the spacing between the joists...if they are spaced 24" then you could cut a hole in your closet and build a wall ladder...if 16 " you would have to "box in", opening after you cut a section out of 1 or 2 ceiling joists; and brace-in around it provide rigidity.

In the hallway you would have to do the same thing to fit your drop-down stairs, and of course in the hallway you would want to trim it out...
You need carpentry skill, sawsall, and skillsaw, squares, nailing /fastening equipment, and assorted basic carpentry tools...If you have tools and gumption to take on a project like this, you could do it :thumbsup: ...maybe go to hopot and buy a remodeling book that addresses those type of stairs or anything where it shows cutting a wall or ceiling open and finishing it out, after you read it and see an explanation of how-to; You will know if you can tackle this job.

I rate this a medium skill level of carpentry...A contractor would probably charge upwards of $500 or so to come and do this. you can invest in some tools and have something to show for it afterward; and for less money...imho, lw :smokin: