cmose,
As I understand it, you have a 3/8" b. cherry you want to nail/staple down to a plywood substrate installed over a concrete slab that has not been tested for mc. It's simple:
1) use Taylor's Lockdown moisture barrier and their Meta -Tec addhesive for wood,2071. http://www.wftaylor.com/pdf_manual/lockdown5.pdf
2) cut your plywood (I'd use 5/8" or 3/4" for staple down) into 16" by 8' strips or 2 by 8 and glue them down to your slab running 90 deg. to your flooring direction. Be sure to kerf the backside 1/2 the depth of the plywood (5/16" for 5/8", 3/8" for 3/4"). Space them 1/4" apart or so. No need to be super clean. You'll have a strong, well bonded subfloor ready to nail that 3/8 to that has a moisture warranty. Keep it simple!

Thanks!!