Well, we have been trying to get our Alteon AD3 (Ace Director 3) to do both SLB and NAT at the same time, which is amazingly difficult. At any we finally got it working. Check it out:

Quick guide to configuring Alteon Webswitch AD3 with VSLB (Virtual Server Load Balancing) and outbound connectivity via PIP/NAT (Network Address Translation) + (Proxy IP)

Configure gateway interface for the VSLB server farm

Execute commands as shown below line by line:

Step 1:
/cfg/ip
if 1
mask 255.255.255.0
addr x.x.x.x where X is the gateway configured on the VSLB machines
ena

Step 2:
/cfg/ip
if 2
mask x.x.x.x where X is the subnet mask for your configured PUBLIC IP space given to you by your provider
addr x.x.x.x same as step 1
ena

Step 3:
/cfg/ip
gw (choose number 1)

ena

Step 4:
/cfg/slb/real 1
rip
IP of REAL server (aka one of the machines in the server farm)
ena

***** Repeat the above step as many times as necessary for your environment changing the number (in this case 1) incrementally for each new machine added *****

Step 5:
/cfg/slb/group 1
add 1
add X (repeat this step changing X to reflect the number assigned to the REAL servers assigned in step 3)

Step 6:
/cfg/slb/virt 1
vip
PUBLIC IP used as VIP (Virtual IP) for the cluster
ena
group 1

Step 7:
/cfg/slb/port external interface (to the internet) is connected to
client
e (enable client processing on this port)

/cfg/slb/port internal interface (to servers) is connected to
server
e (enable server processing on this port)

Step 8:
/cfg/slb/on (turn SLB ON)

Step 9:
apply (applies the above configuration and now you have working inbound SLB)

Step 10:
/cfg/slb/adv/matrix
d (disable VMA as its benefits may outweight IP allocation)

Step 11:
/cfg/slb/filt 10
dip x.x.x.x where X is the IP configured as the gateway of the server farm
dmask 255.255.255.255 (designates /32)
act nat
nat source
ena

Step 12:
/cfg/slb/filt 100
sip x.x.x.x (where X is the IP subnet used for the server farm)
smask x.x.x.x (where x is the subnet used for the SIP configured above)
action nat
nat enable

Step 13:
/cfg/slb/filt 224
ena

Step 14:
/cfg/slb/port where PORT is the one physically connected to the servers
filt ena
add 100
add 224

Step 15:
/cfg/slb/port where PORT is the one physically connected to the servers (this convention is not necessary but is clean and straightforward)
pip
proxy ena

Step 16:
apply

ALL DONE!