Can Section 179 tax deduction be applied to Mobile Homes and other capital improvements

Can  Section 179 deduction be used for writing off Mobile home purchases/ capital improvement investments in one year instead of depreciating them over 15 years?My tax accountant claims we can do so by using Section 1789, but heard from others it does not apply to MHP business. http://www.section179.org/Can you share your experience or opnions on that?thanksSema