MatGetVecs and MATMFFD

[Boyce Griffith]

Hi, Folks --

I am using a home-grown "multi-Vec" (i.e., vector of vectors) 
implementation with a PETSc nonlinear solver.  I'd like to be able to use 
PETSc's matrix-free Jacobian with this solver along with a PCCOMPOSITE 
preconditioner; however, it seems like I need to override the default 
implementation of MatGetVecs in order to get this to work.

Is there a kosher way to do this?

Thanks,

-- Boyce