utility elicitation is the process to go from Rational Preferences to a utility function. Its a bad idea to use money to do this, because money is not linear. Consider the best and worst possible events:
\begin{equation} \overline{S}, \underline{S} \end{equation}
We assign the best event to have utility 1, and worst to have utility 0:
\begin{equation} \begin{cases} U(\overline{S}) = 1 \\ U(\underline{S}) = 0 \end{cases} \end{equation}
Given some test event now S, we try to find the p such that we can set up a lottery:
\begin{equation} S \sim [\overline{S}:p; \underline{S}:(1-p)] \end{equation}
because the desirability of S is between the best and worst possible events, the continuity von Neumann and Morgenstern Axiom states that this p exists. Once this p has been figured, we then assign:
\begin{equation} U(S) = p \end{equation}