[plt-scheme] As build troubles

Hello,

I am trying to build PLT from CVS sources on a Sun Sparc, Solaris 2.8
machine.  The make process bombs out with:

./if_mach SPARC SUNOS5 as  -o
mach_dep.o ./sparc_mach_dep.s
^^^^Starting command^^^^
Couldn't execute: No such file or directory
Usage: ./if_mach mach_type os_type command
Currently mach_type = SPARC, os_type = SUNOS5
*** Error code 1
make: Fatal error: Command failed for target `mach_dep.o'

And if I'm reading this correctly, the problem is `as' is not found on my
system.  Is this correct?  Can I work around this, short of building the
GNU binutils?

Thanks,
David