Setup multiple IP addresses on PIX

Can you be more specific in your requirements? You cannot add secondary addresses to a PIX like you can a router.
You can NAT multiple external addresses to multiple internal addresses though, if that's what you need to do..

Only one IP address can be assigned to the external NIC on your PIX 515
But you can assign mulitple addresses to your NAT "pool".
Ex:  ISP has given you the ff: useable IP addresses.
      1.2.3.4 -- 1.2.3.20
 In this case you can assign as ff:
      1.2.3.4                  --> External NIC
      1.2.3.5 - 1.2.3.10   --> Assigned to NAT pool so that internal hosts can browse external resources
      1.2.3.6                  --> Assigned to PAT Backup in case your NAT pool is exhausted
      1.2.3.7 - 1.2.3.15   --> Use for STATIC NAT or STATIC PAT to publish internal resources or create ACL
      1.2.3.16 -1.2.3.20  --> Extra IP's just in case

I hope this answers your question. Assign points to lrmoore. I am just elaborating on his answer.
Search the CISCO website for "pix configurations", and you will find numerous examples.

Yes.  I am trying to NAT multiple external addresses to multiple internal addresses...please advise

JEEGO-

Thanks for the input...I am browsing PIX configs right now...

You can create multiple statics:

   static (inside,outside) <public IP1> <private IP1> netmask 255.255.255.255
   static (inside,outside) <public IP2> <private IP2> netmask 255.255.255.255
   static (inside,outside) <public IP3> <private IP3> netmask 255.255.255.255

Example:
    static (inside,outside) 13.45.67.8 192.168.100.100 netmask 255.255.255.255
    static (inside,outside) 13.45.67.9 192.168.100.101 netmask 255.255.255.255
    static (inside,outside) 13.45.67.10 192.168.100.102 netmask 255.255.255.255

the inside, outside is perfect...now these outside addressess are going to be used for VPN...meaning, a user at home will vpn to 13.45.67.8...the PIX will nat this to a 1710 router thats WAN int is set to a private address on my network, the 1710 supports VPN connectivity.  I belive I need to setup the PIX with sysopt...please advise.