R help - Apr 2012 - Using FME modCost with multiple independent variables

I am attempting to calibrate a forest growth model using FME. I have 
several spatially separate plots with time series growth data for 
each(eg, height, basal area, etc.). Thus 2 independent variables: time 
and plot.

Is there a way that I can calculate a model cost that takes into account 
these different plots? I notice in the documentation for the modCost 
function that there is a note stating that using more than one 
independent variable should be possible in the future, and was wondering 
if anyone has managed this? Or if there is a way I can achieve this, it 
would be interesting to know how.

Thanks,

Jack

-- 
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.