hmmm I havent done it myself yet but it looks like it would work if you convert the nimserver to dhcp usage and than install all clients (linux and AIX) this way ... but still with NIM functionality...
If you are creating your RedHat server as an LPAR behind a VIO server, you can upload the RH installation *.iso disk image to vio:/var/vio/VMLibrary, create a virtual CD drive for your RH LPAR, and...