In forms mode you can open a Blank Form where you can make entries, but I don't know if this gets included in an e-filing. It does get included in the official forms for filing when you print.
I don't think that the IRS automated systems would detect any problem which ever way you reported it. An explanation statement would only be reviewed if the tax return gets examined by a human, which in most cases only happens if the automated system kicks it out for review.
