ISO with Application not Available in Packages

Greetings,

I have found the instructions for building custom ISO images, adding features via packages. Does anyone know how to do this for applications that do not have a package? I have a relatively old and obscure application that I wish to load into RAM along with Alpine (about 600MB) to increase NFS read speed, which the application uses extensively. I can create the ISO with NFS and SSH, but because there is no package for this app, seem stuck at this point.

Any ideas on how to create the ISO with non-packaged applications?

Cheers,
- SteveN