Adding to the user fields in Freeradius

[saampson]

Hello,
I am in need to add some info to the user fields in Freeradius. I need to be able to put in the serial number of the device among others as well. when I am done creating the user it needs to look like this.

radius Cleartext-Password := "radius", RADWIN_SerialNumber == "uniqueserial"
RADWIN_ServiceCategory = 5,
RADWIN_Name = "HSU1-Left_test",
RADWIN_Location = "Left-HSU1_test",
RADWIN_Vlan = 200,
RADWIN_RegisterAvailability = 1
I can get it to work if I manually add this to the user file. If I need to change anything it will be very annoying. So is there anyway to edit the Freeradius user area to be able to add custom fields? Thanks for any help!