Injecting my own Dot11 FCS in Scapy

I am trying to generate a Probe Request wifi packet into air. For this I am using Alfa-AWUS036NHA-Wireless-Network-Adapter on FC19. Set it in monitor mode and issuing following command.

Quote:

>>> packet=RadioTap()/Dot11(type=0,subtype=4,addr1="ff:ff:ff:ff:ff:ff", addr2="00:11:22:33:44:55",addr3="ff:ff:ff:ff:ff:ff")/Dot11Elt(ID="SSID", info="4366ap") >>> sendp(packet,count=10,iface="mon0") .......... Sent 10 packets.

It auto-calculates the FCS and appends to the packet. I can see it on wireshark. Can someone please help tell the procedure where I can insert my own FCS value.

Thanks in advance.
uv.