R help - May 2009 - AFT-model with time-dependent covariates

Dear R-community, 
Dear Prof. Therneau,

I would like to fit an AFT-model with time-dependent covariates and
right-censored data.

Searching the mailing list for information on the subject, I found some old
posts which said it didn't work back then.

My questions:
(1) Has this kind of fitting already been implemented in the survival library in
R?
(2) If not: Are there any alternatives/ workarounds in order to get this job
done in R anyways?
(3) Can you recommend any other (commercial) software to fit this model?

Thanks for your great help, I areally ppreciate it!

All the best
Philipp

The coding for an AFT model with time-dependent covariates will be very hard, 
and I don't know of anyone who has done it.  (But I don't keep watch of
other
survival packages, so something might be there).
 
  In a Cox model, a subject's risk depends only on the current value of
his/her
covariates; in an AFT model the risk depends on the entire covariate history.  
(My 'accelerated age' is the sum of all the extra years I have ever
gained).
Coding this is not theoretically complex, but would be a pain-in-the-rear amount
of bookkeeping.
  
  	Terry Therneau