GNU dc is real easy to install, if you still want to get it working you could try installing GNU dc, its available as: bc-1.04.tar.gz from all the GNU distributers, got mine from:
ftp://src.doc.ic.ac.uk/gnu/bc-1.04.tar.gz
It is a dream to install, I just did:
% gunzip bc-1.04.tar.gz % tar xf bc-1.04.tar % cd bc-1.04 % configure % make dcand there was a nice shiny new dc ready to copy to my binary directory. It's a lot faster than all the old dc's and it works with perl-rsa!
Note dc-1.1 (the one that comes with bc-1.04) has a new operator, the | (pipe) symbol. It computes modular exponentiation. (a b c | means a ^ b mod c).