ROI Regressor calculation using Taylor series

dear rest-team,

I am interested into the adaptation of the time course calculation of different ROI regressors in REST in the following way:
For the reason of small correction of time-shifts the idea is to differentiate the time courses, similar to the idea of taylor series:
               f(t)=f(t=0)+ df/dt I(t=0) + d^2f/d^2t I(t=0)+...

Any feedback towards this idea and its potential implementation possibilities in REST would be highly appreciated,