Galatius and Randal-Williams proved the following generalized Mumford conjecture in their joint paper, "Stable Moduli spaces of High Dimensional Manifolds". For each characteristic class of oriented $2n$-dimensional vector bundles $c\in H^{2n+k}(BSO(2n))$, one can define the associated generalized Mumford–Morita–Miller class of a smooth fiber bundle $\pi: E\to B$ with oriented $2n$-dimensional fibers as $\kappa_c(E)=\pi_!(c(T_vE))\in H^k(B),$ where $T_v(E) = Ker(D\pi)$ is the fiberwise tangent bundle of $\pi$. When the fiber is taken to be $W_g=\#^g S^n\times S^n$, the connected sum of $g$ copies of $S^n\times S^n,$ there is a corresponding universal class $\kappa_c\in H^k(BDiff(W_g, D^{2n}))$ which for $k>0$ is compatible with increasing $g$.

Theorem (Galatius-R-W) Let $2n>4$ and let $\mathcal{B}\subset H^*(BSO(2n);\mathbb{Q})$ be the set of monomials in the classes $e, p_{n−1}, p_{n−2},...,p_{\left\lceil\frac{n+1}{4}\right\rceil}$ of total degree greater than $2n$. Then the natural map $$\mathbb{Q}[\kappa_c|c\in\mathcal{B}]=\lim_{\longleftarrow g}H^*(BDiff(W_g,D^{2n});\mathbb{Q})$$ is an isomorphism.

I would like to compute $$\lim_{\longleftarrow g}H^*(BDiff(W_{g},D^{\infty});\mathbb{Q}).$$ Under the the isomorphism of G-R-W, this reduces to computing the MMM classes $\kappa_c$ and the classes $e,p_{\infty}$. How do I determine such classes?

Thanks!