Symbolic solution for system of equations

Hello. I'm trying to solve symbolically a equation of type M*Z_DDot+C*Z_Dot+K*Z=F, where M, C, K and F are 3x3 matrices. I want to solve for Z, which is a 3x1 vector containing the displacement of 3 masses. I've written a matlab script but it seems i cannot get around a problem regarding the boundary conditions. I'm using dsolve command and so far i was able to define only the initial displacement of the masses. Please tell me how do I define the velocity and acceleration boundary conditions using dsolve command. I can post the matlab script if necessary. Thank you very much.