F#, 233 chars
let[|a;b;c|],(+),z,(!)=stdin.ReadLine().Split[|' '|]|>Array.map int,String.replicate," ",printfn"%s"
for r in 1..c do
for n in 1..a do !(b+(a-n+z^"/"^2*n-2+z^"\\"^a-n+z))
for n in 1..a do !(b+(n-1+z^"\\"^2*a-2*n+z^"/"^n-1+z))
Fun! A couple new bits for my F# code-golf arsenal:
- using
stdin rather than the cumbersome System.Console stuff
- abusing operator overloading/redefinition
