VPN over dynamic Internet IP address?

[Cindy Ding <cindy_(_at_)_cindy-pc_(_dot_)_willowglen_(_dot_)_com_(_dot_)_my>]

Hi,

I'm trying to implement VPN on two private networks over Internet.

At site A, I have a few FIXED valied Internet IP addresses, which I used
on router and firewall machine.  The internal networks are un-routable
from site B, of course.

At site B, the ISP assigns my IP address dynamically each time I connect,
the router (ISDN) is doing the NAT for any packages in and out of the
internal networks. (The Malaysia ISP won't give fixed IP address unless
I'm using leased-line, and leased-line in this country is sooooooo
expensive.)

Since the external IP address at site B is always changing, can I
implement VPN on this?  I looked through the manuals I can find, but
nowhere mentioned this. I GUESS the answer is NO. (I wonder if I'm asking
a stupid question. :-) ) 

If I use an impossible IP address (such as 1.2.3.4) as the external IP
address for site B, will the VPN be smart enough to find the way for me?

Please reply to me since I'm not subscribing the mailing list anymore.
Thanks a lot!

Cindy Ding
Senior System Engineer
Willowglen MSC Sdn Bhd
No 1-2, Jalan 2/149B
Taman Sri Endah
Bandar Baru Sri Petaling
57000 Kuala Lumpur, Malaysia
Tel: (603) 9587104
Fax: (603) 9583904
Email: cindy_(_at_)_willowglen_(_dot_)_com_(_dot_)_my