Laid out below are the instruction to get a SpeedTouch Pro working with DHCP Spoofing. This should allow your PC to be seen by the outside world, so please take whatever steps you feel are necessary to protect your PC and data, i.e. Firewall, anti-virus etc. 
My thanks go to Petersen and Mr Saffron for the written instructions. I've just tidied them up and added the pics.


Go to Phonebook and delete every entry. Then delete all the entries in PPP, CIP, PPTP and Bridge. DO NOT TOUCH the Routing section, or you may not be able to talk to your modem/router. Then go back to the Phonebook section, and delete the entries you've just deleted!!! (don't blame me, blame Alcatel).
You should end up with a screen like that below.

Ok, now you've got an empty phonebook, add a new entry with a name starting with DHCP (mine is called DHCP_Spoof).
For the UK, set VPI 0, VCI 38.
Select ppp. Click on Add.

Now go to the ppp page and click on configure.

Enter your username and password. I've masked mine for obvious reasons.
Set the following:
Connection sharing=everybody
Destination networks = all networks
Leave specific network empty
Tick the "Address Translation (NAT-PAT)" box.
Put your isp's dns servers in if you wish
Local IP = none
Remote IP =none
Mode = dial-in
Leave idle time limit blank
Tick LCP
Untick PAP
Ttick ACCOMP
Click on Apply, then Save All

Next go to DHCP screen. Select DHCP Server, then hit the advanced button,
Tick the DHCP spoofing box. The rest should be left as default.
Click on Apply, then Save All

TIP: The 'timeout waiting for ppp linkup' can be increased if the isp's servers are being laggy logging you in.

Go to the dial-in screen, and make sure your connection is DOWN. If it isn't, hang up.
Click on Save All.
Now you can issue a DHCP refresh to the pc (ipconfig /renew), and it should automatically spoof the ip for you.
Rev1.3 24/2/02