Seasonal service (usually Sat. only) may restart this Winter. Right now, you'd have to overnight in EWR and fly CO from there. There are no flights that connect to the early morning flight on CO out of EWR from either MSP or DTW.
The same would apply to the return--another overnight in EWR.
For the price of the hotel stay and inconvenience/lost time associated with the layovers each way, try NW or CO to SJU and purchase a separate ticket on AA out of SJU.
[This message has been edited by PARSpro (edited 08-11-2002).]