Since many components of the tree use 'autoconf' generated configure scripts, you must configure the tree on the host that you wish to configure for.
A corollary to this is that you also need to have a C compiler available at configure time. `cc' is used, unless you specify another compiler by setting the environment variable CC during the configuration. The scripts and Makefiles used to build Cygnus releases do something like this:
CC='cc -Xs' ../progressive/configure sparc-sun-solaris2 etc
You are likely to run into problems if you configure with a different compiler than you use during build time. For example, if you configure using `gcc', and compile with `cc' on SunOS 4.x, you'll have problems with programs that expect `const' to be useful and valid, since this feature is tested for at configure time.