From reading various forum post, it appears this is not possible, but I thought it would be worth a try.
According to the wiki article (http://wiki.logos.com/Reading_Plans), it appears as though you can hand enter a large number of passages into the "new reference range" box and it should break your reading plan down according to your detailed passages (e.g. Harmony of the Gospels, etc.).
I tried putting in my complete ESV M'Cheyne Plan (slightly different from the one in Logos [the fourth reading follows a different pattern]). The problem is even with reading from all 365 days defined individually (in this format: Gen 1, Gen 2, Gen 3, Gen 4, with "|" in between the separate readings) Logos still breaks it down in its own way. If you look at the year as a whole it follows the plan, but the individual days are off due to Logos trying to break things down evenly.
Any way to do this? The only other option I can think of, so I can have access on my iPad, is to create a note document with the reading plan. Which is less than ideal.
Thanks!