well, seems that my problem is too bored since no one respond...
finally i managed to get all things work. just added one line inside the bootp() call in the /etc/pcmcia/network script, enabling my xircom card enter promisc mode then dhcp can now get an IP successfully. later on the card leave promiscous mode BUT it still receive and transmit packets. this is what i wanted and achieved:
1. dhcp works 2. no need to be in promisc mode
still not perfect are the quite serious TX errors which populate my "dmesg"
having used this xircom cardbus realport for over a year, the card really shines - but with quite a lot of effort in making it work in its area.