Watch the Reharmonizations online guitar lesson by John Stowell from Modern Jazz Improv
My basic rule for using the implied V chord is that a change needs to happen for at least one bar for any additional harmony to be added. A good way to start to integrate the implied V concept into your playing is to begin with even length phrases (i.e., one bar of C maj7, one bar of G7 altered). Eventually you can play less predictable asymmetrical phrases. The implied V can happen anywhere in a progression (i.e., over a I,Ii,III chord, etc.).