Sure - you can install Chef as a gem as non-root if you're running rvm or a similar userspace gem manager.
$ gem install chef
Fetching: chef-11.6.0.gem (100%)
Successfully installed chef-11.6.0
1 gem installed
$ which chef-solo
/Users/tpot/.rvm/gems/ruby-1.9.3-p327/bin/chef-solo