Code:

/* ----------------------- Optional MCU Description ------------------------ */

/* The following configurations have working defaults in usbdrv.h. You
 * usually don't need to set them explicitly. Only if you want to run
 * the driver on a device which is not yet supported or with a compiler
 * which is not fully supported (such as IAR C) or if you use a differnt
 * interrupt than INT0, you may have to define some of these.
 */
 #define USB_INTR_CFG            MCUCR
 //#define USB_INTR_CFG_SET        ((1 << ISC00) | (1 << ISC01)) 
 #define USB_INTR_CFG_SET        (1 << ISC01)
 #define USB_INTR_CFG_CLR        0
 #define USB_INTR_ENABLE         GIMSK 
 #define USB_INTR_ENABLE_BIT     INT0 
 #define USB_INTR_PENDING        GIFR 
 #define USB_INTR_PENDING_BIT    INTF0 
 #define USB_INTR_VECTOR         SIG_INTERRUPT0 

Code:

General Description:
This file is an example configuration (with inline documentation) for the USB
driver. It configures AVR-USB for an ATMega8 with USB D+ connected to Port D
bit 2 (which is also hardware interrupt 0) and USB D- to Port D bit 0. You may
wire the lines to any other port, as long as D+ is also wired to INT0.
To create your own usbconfig.h file, copy this file to the directory
containing "usbdrv" (that is your project firmware source directory) and
rename it to "usbconfig.h". Then edit it accordingly.
*/

/* ---------------------------- Hardware Config ---------------------------- */

#define USB_CFG_IOPORTNAME      B
/* This is the port where the USB bus is connected. When you configure it to
 * "B", the registers PORTB, PINB and DDRB will be used.
 */
#define USB_CFG_DMINUS_BIT      0
/* This is the bit number in USB_CFG_IOPORT where the USB D- line is connected.
 * This may be any bit in the port.
 */
#define USB_CFG_DPLUS_BIT       1
/* This is the bit number in USB_CFG_IOPORT where the USB D+ line is connected.
 * This may be any bit in the port. Please note that D+ must also be connected
 * to interrupt pin INT0!
 */