This is a very interesting question. As you state, you are not referring to a new series of entitlement programs, but rather to a form of structured and sanctioned paths which those in the lower economic echelons could use to rise above their current positions.
I agree with you in the essence that economic betterment must be sought by all. However, empowering people to do this cannot come from the government, rather it must come from the people themselves. If government wishes to see that idea foster and grow the best action for them to take is to not be a hindrance.
Creative new lending programs, sanctioned vocational training, in addition to all of the programs that currently exist for the same intended purpose, make for good headlines and photo-ops for local politicians, but yield little to no positive effect on helping those with ambition, skill and desire to rise to the top.
The best thing that government can do is get out of the way. Reduce the level of regulations, restrictions, paperwork, etc that a microbusiness needs to navigate through just to get started. Many a wonderful idea has been stifled by such bureaucracy.
In the past so called "rags to riches" stories were far more prevalent simply because there were not so many hurdles to clear in order to achieve success. Skill, talent, tenacity and courage were the primary ingredients to gain success in America. Now, you need to be able to disseminate volumes of governmental gobbeldy-goop simply to get to the starting line.
Elimination of such governmental barriers coupled with an adherence to "natural" fairness (no bailouts for large corporations and small business alike; you fail, you lose) would restore the natural pathways toward success. It would reward real achievement and prove once again that a population left to act on its own best interest does so quite well.