Sorting on dates using long

[Björn Ekengren]

Hello,
I am trying to get sort by date to work. The dates are of form yyyyMMddhhmm and 
it seems that sort sees them as Integers and discards the last four numbers 
since an integer isn't large enough. I tried using SortField.STRING instead but 
then constantrangequery breaks (date:[200501010101 TO 200601010101] returns 0 
hits). Is it possible to sort using a long or are there any other solutions ? I 
would like to avoid splitting the date into several fields by other reasons.
 
--regards