Uhh guys, co.com will definately allow you to book an all-codeshare flight.

I.E. EWR-STL, departing 2/4/02 and returning 2/6/02, all segments operated by Northwest:

From www.co.com:

704.50 USD Total including taxes


Continental 6225 | 6201
Aircraft: 320 | D9S
Mon - Feb 4, 2002
New York/ Newark, NJ (EWR) 4:15 PM
St. Louis, MO (STL) 7:54 PM
4 hr 39 mi
OnePass miles: 1,000
Connect in Detroit, MI (DTW).
Continental flight 6225 operated by Northwest Airlines.
Continental flight 6201 operated by Northwest Airlines.


Continental 6202 | 5366
Aircraft: D9S | D9S
Wed - Feb 6, 2002 St. Louis, MO (STL) 8:25 AM
New York/ Newark, NJ (EWR) 1:37 PM
4 hr 12 mi
OnePass miles: 1,000
Connect in Detroit, MI (DTW).
Continental flight 6202 operated by Northwest Airlines.
Continental flight 5366 operated by Northwest Airlines.