K-theory as an Eilenberg-Maclane spectrum

For an additive Waldhausen category linear over a ring $k$, the corresponding $K$-theory spectrum is a module spectrum over the $K$-theory spectrum of $k$. Thus if $k$ is a finite field of characteristic $p$, then after localization at $p$, we obtain an Eilenberg-Maclane spectrum -- in other words, a chain complex. We propose an elementary and direct construction of this chain complex that behaves well in families and uses only method of homological algebra (in particular, the notions of a ring spectrum and a module spectrum are not used).