As swiped from this post by IceWindius

701g DMZ setup

1. Go to the Actiontec's menu of 192.168.0.1
2. Go into advance setup
3. Click through menu's and select DMZ
4. Give the WAN interface of the router an IP from the subnet range of the 701g, like 192.168.0.50
6. Enter that IP in the DMZ zone of the 701g
7. Disable DHCP and wireless on the 701g, as its essentially gonna doing nothing more then passing all packets to the router
8. Save settings on 701g

Router Setup
1. Enter menu of router and put in the IP you selected on DMZed section of the 701g in the WAN interface of the router (192.168.0.50 in this case)
2. Setup the rest of your portfowarding, static routing ect. that you need to do
3. Save settings on your router

...and you should be good to go!

Added:
Additional steps if your router has a LAN IP address of 192.168.0.1:
1. Enter the menu of the router by going to 192.168.0.1
2. Change the router's LAN address to 192.168.1.1
3. Save settings on your router
4. Change your computer's IP address so that it will be in the 192.168.1.XXX subnet, so something like 192.168.1.10. (Do not use 192.168.1.1 for your computer's IP address!)
5. Enter the menu of the router by going to 192.168.1.1
6. Setup the port forwarding to your computer's new IP address.
7. Save settings on your router

...and you should be good to go!