There is no reason we can't use TCL. Obviously if the install system is going to run OpenACS TCL will run on the system. If we really want to make and installer we might consider using tcl source distribution to create a customize tclsh to do the installation. The installer would then be a bit easier to control. We could also look into using starkits to distribute the installer also.
It should be that hard to use a portable TCL solution for an installer I have done with customer projects, successfully, in serveral instances.
