Maybe this can be done by hand, but if not, it is a consequence of more general central limit theorems for additive functionals of Markov chains, i.e. for expressions of the form $$S_n = \frac 1 {\sqrt n}\sum_{k=1}^n [f(X_k)-\pi(f)]$$ where $(X_n)$ is an ergodic Markov chain with invariant measure $\pi$. Here the chain is the sequence of jumps, and he function is the identity. Possible reference: G. Jones, "On the Markov chain central limit theorem", Probability Surveys 1 (2004), 299-320 (link)(link).
About estimating the diffusion parameter, the increments of your walk are orthogonal in distribution, so you can compute the expected square norm of $S_n$ directly by expanding the sum...