yes you can use Autoloading to dynamically catch every call to a an old sub and redirect it.

you can even automatically create these new subs, such that the next call will be faster.

if you just want a static mapping you can use something like

*myNewPackage::b=*myPackage::b

in a loop over a hash defining the mappings.

That are untested ideas, hope you can elaborate it yourself. :)

UPDATE: link repaired.