I found the following in the archives:
http://mail-index.netbsd.org/port-i386/2001/03/09/0009.html

However, this does not appear to work for this model. After recompiling
-current with the diffs above the system, modified for the appropriate
product id, becomes unusable and the device remains unconfigured. The
system boots, however, any attempt to login fails and a kernel message
is logged:
nsendsig: bad version 0

the device is configured as such in this case:
ex0 at cardbus1 dev 0 function 0: 3Com 3c656bt Ethernet

dmesg output before patch:
3Com Corporation, 3CCFEM656BT, LAN, 0 (manufacturer 0x0, product 0x0)
3Com product 0x6560 (Ethernet network, revision 0x02) at cardbus1 dev 0
function 0 not configured

James Baldwin

> -----Original Message-----
> From: Baldwin, James
> Sent: Sunday, September 07, 2003 3:00 AM
> To: port-i386@NetBSD.org
> Subject: 3CCFEM656BT
>=20
> Is anyone currently working on porting the 3CCFEM656BT 3Com Cardbus
> Network card? I see the product id in dev/cardbus/cardbusdevs.h,
> however, it is not included in ex_cardbus_products[] from
> dev/cardbus/if_ex_cardbus.h. I'm not sure how to find out any of the
> information reqired for the softc clags, CSR flags, or card type. If
> anyone has a patch for the 3CCFEM656, or ideas where I could find the
> appropriate information, I'd be grateful.
>=20
> Excerpt from cardbusdevs.h:
> #define CARDBUS_PRODUCT_3COM_3C656_E    0x6560          /* 3CCFEM656
> 10/100 Ethe
> rnet */
>=20
> Excerpt from if_ex_cardbus.c:
> const struct ex_cardbus_product {
>         u_int32_t       ecp_prodid;     /* CardBus product ID */
>         int             ecp_flags;      /* initial softc flags */
>         pcireg_t        ecp_csr;        /* PCI CSR flags */
>         int             ecp_cardtype;   /* card type */
>         const char      *ecp_name;      /* device name */
> } ex_cardbus_products[] =3D {
>         { CARDBUS_PRODUCT_3COM_3C575TX,
>           EX_CONF_MII | EX_CONF_EEPROM_OFF | EX_CONF_EEPROM_8BIT,
>           CARDBUS_COMMAND_IO_ENABLE | CARDBUS_COMMAND_MASTER_ENABLE,
>           EX_CB_BOOMERANG,
>           "3c575-TX Ethernet" },
>=20
>         { CARDBUS
> EX_CONF_90XB|EX_CONF_MII|EX_CONF_INV_LED_POLARITY |
>             EX_CONF_EEPROM_OFF | EX_CONF_EEPROM_8BIT,
>           CARDBUS_COMMAND_IO_ENABLE | CARDBUS_COMMAND_MEM_ENABLE |
>               CARDBUS_COMMAND_MASTER_ENABLE,
>           EX_CB_CYCLONE,
>           "3c575B-TX Ethernet" },
>=20
>         { CARDBUS_PRODUCT_3COM_3C575CTX,
>           EX_CONF_90XB | EX_CONF_PHY_POWER | EX_CONF_EEPROM_OFF |
>             EX_CONF_EEPROM_8BIT,
>           CARDBUS_COMMAND_IO_ENABLE | CARDBUS_COMMAND_MEM_ENABLE |
>               CARDBUS_COMMAND_MASTER_ENABLE,
>           EX_CB_CYCLONE,
>           "3c575CT Ethernet" },
>=20
>         { 0,
>           0,
>           0,
>           0,
>           NULL },
> };_PRODUCT_3COM_3C575BTX,