You can do it in three steps by hand:
Select the columns
Choose standardize attributes and then recode.
Recode all .'s to 0.
If you want to do it by jsl, you could do it like this:
dt=current data table();
colnames = dt << get column names( numeric,string );
For( i = 1, i <= N Items( colnames ), i++,
column(dt,colnames[i])[dt<<get rows where(is missing(as column(dt,colnames[i])))]=0;
);
Kind regards, Thomas