Wake-up PC from sleep mode using PIC24FJ256GB106
You will need to alter the config descriptor to enable the device to wake the PC from sleep. Specifically this means setting bit 5 in the bmAttributes byte. Have a look through the Microchip USB stack (e.g. config_desc.c or whatever it's named currently), there are plenty of comments to guide you.  




  wTotalLengthequals the number of bytes in the configuration descriptor and
  all of its subordinate descriptors.
  bNumInterfacesequals the number of interfaces in the configuration. The
  minimum is 01h.
  bConfigurationValue identifies the configuration for Get Configuration and
  Set Configuration requests and must be 01h or higher. A Set Configuration
  request with a value of zero causes the device to enter the Not Configured state.
  iConfiguration is an index to a string that describes the configuration. This
  value is zero if there is no string descriptor.
  bmAttributes sets bit 6 = 1 if the device is self-powered and zero if bus pow-ered. Bit 5 = 1 if the device supports the remote wakeup feature, which enables
  a suspended USB device to tell the host that the device wants to communicate.
  The other bits in the field are unused. Bits 4..0 must be zero. Bit 7 must equal 1
  for compatibility with USB 1.0
  bMaxPower.Specifies how much bus current a device requires. For USB 2.0,
  bMaxPower is in units of 2 mA. If the device requires 200 mA, bMax-Power=64h. For SuperSpeed, bMaxPower is in units of 8 mA.


Above table and info from "USB Complete" by Jan Axelson - an excellent book on all things USB.