You can also do it by specifying the rpar arguments exactly as they appear when you run the regular mlogit() command. So for your example:
rpar = list("A:scan.id"="n", "C:scan.id"="n", ...)
where they named list must be quoted because of the ":" (I think, it may just be for "(", but it works with quotes either way) -- see footnote 20 p. 24 of documentation. Also see 1st paragraph of p.26 of documentation about having to list the entire name of individual specific coefficients. I had a similar problem when trying to just use scan.id but it stated working when I started putting the A:scan.id = argument instead. I believe you can do this with your data, as long as you set panel=F which I think is the only time the id.var=scan.id is invoked for multiple observation on the same person. If you do in fact have a panel, then don't use that variable and use the other variables you want to simulate as normal or another distribution. I'd also recommend using halton=NA argument if you have a large as it speeds up the simulation significantly.
