It is possible to establish an ActiveSync connection over any Serial Port on your Colibri module.
On the Colibri module:
Open the Network & Dial-up Connections applet from the Settings menu in the Start menu. Make a new connection by using a suitable name for your connection like "CoM1 ActiveSync" and choose Direct Connection from the radio button group. Click the Next button and accept the default settings, unless you are using another serial port than CoM1.
Go to the Control Panel and open the PC Connection applet. Change you connection to the the new connection you just made. Therefore, click on the Change button and select the desired ActiveSync connection from the list (CoM1 ActiveSync).
From the Run... item in the Start menu, run "repllog.exe". The device should attempt to connect to your PC and the status circle for ActiveSync should turn green. Make sure ActiveSync has the connected CoM port enabled on you Workstation. If the connection is established successfully, ActiveSync could ask you if you want to establish a partnership.