You would best safest by having an architect do the plans. The particular layout will determine how and where best to create the access and nake sure all the necessary support is designed in.

For instance, floor joists will have to be cut and that load will have to be transferred to other load bearing structures(walls/posts/etc.)

There has to be sufficient room for the actual staircase to be built to code---height and width of the treads---so it is safe and comfortable to use.