hi my son did the 45min catnap thing from a very early age. I actually found that moveing to the 4hr easy helped b/c it gave me more time to get him back to sleep with pupd. I did this cold turkey as I though the transition thing was just to confusing.
so our day looked something like this:
wake bf 6
nap 8 for 45min-8:45, spent 40min doing pupd, slept for another 45min---10:15am
bf 10:15
nap 12:15 for 45min-1pm, spent 40min doing pupd, slept until 2:15
bf 2:15
catnap 4
bath, bf at 6:30 bed
eventually his naps got much better---and then he had longer A times 2 1/2hrs