Can I have on a single ruby installation multimple RubyGem Manager using RVM?

I'm using RVM to maintain different ruby installations. But I would like to have, for a single ruby installation, different versions of RubyGems Manager. I see that I can only have one only RubyGem Manager on each Ruby installation. The reason for having different versions of RubyGem is that I'm installing a very old version of RoR applications that needs a old version of RubyGems but on the same version of Ruby I use for other projects, that want a newer RubyGem. Do you know if it wo开发者_如何学运维uld be possible to install a new, separate, copy of Ruby where I can install a specific version of RubyGem and all gems I want? It seems that even gemset can't help to do what I need because it can only manage different versions of gems but on the same RubyGem Manager. What am I doing wrong? Thanks for you help!

It is possible with named rubies basically it goes down to:

rvm install 1.8.7-old
rvm use 1.8.7-old
rvm rubygems 1.3.6