How to bring a PDE with A * d^5/(dx^4*dt) + B * d^4/(dx^2*dt^2) = 0 in PDE Toolbox Format

Greetings,

I'm solving a PDE with mixed derivatives of the form A * d^5/(dx^4*dt) + B * d^4/(dx^2*dt^2) = 0 where A and B are constant coefficients. The problem is to seperate the spatial from the time derivative and to solve for the 1st and 2nd time derivative. The type is hyperbolic but with the 1st time derivative as well and the highes spatial derivative is 4th.

Kind Regards