You can use this for DigiMesh, but you have to change the firmware. That is easy done with the X-CTU application from Digi (Select the modem type "XB24-DM" and firmware "XBee DigiMesh 2.4" firmware and force a firmware upgrade). You will also find the documentation for DigiMesh on the digi site.
Digi.com quote: "XBee DigiMesh 2.4 hardware note: The XBee and XBee-PRO DigiMesh 2.4 share hardware with the XBee and XBee-PRO 802.15.4 modules. As a result, these modules can be “converted” from one platform to another by loading different firmware onto a given module."
Good luck!