What you need for calculating $E_a$ or $\Delta H^\ddagger$ and $\Delta S^\ddagger$ are rate constants at different temperatures. So the real question here is how to get the rate constant from a, what you call "specific end point". I am assuming here that you are talking about reactant/product concentrations at a specific time point and you also know the the starting concentrations.
This is in principle, at least for simple lower order reactions, possible, but only if you know the order of the reaction. How to do it depends on the order of reaction and the setup.
For example for zero order:
$ A \rightarrow B $
If we got 10% left after 90 seconds and we started with a concentration of 1 M this means:
Or for a second order reaction following $2A \rightarrow B$:
Let's say again that after 90 seconds 10% of A was left and we started with 1M:
Please note that this is very close related to half-lifes of reactions. You might want to look into how to calculate those, the reverse process is how you can calculate the rate constant knowing the conversion and the starting concentration.