I've been compiling my software on my i386 linux box and then performing the final link on the vax.  It is much faster for me since my 3100 is only a 4 MHz machine and it takes a while to build the applications I want.  For example, emacs 21.7 takes about 3 hours to gcc+ld on my vax, but only took about 10 minutes cross compile, and then about 10 minutes to fully ld and install on the vax itself.  I used nfs to mount my i386 partition on the vax and perform the final ld and install from the i386 exported filesystem.

If you have another machine, such as a sparc, alpha, powerpc or pentium box that uses NetBSD or Linux (or Cygnus on WinNT), then build the vax cross gcc and do the compilations there (via nfs) and then perform the final link and install on the vax.