Gotta love the weighted dips.
Shrek, for warmup, a good 20 reps or so cable pushdown works a treat (warms up the elbow joint nicely). Or, close grip pushups on the dumbbell rack (the incline takes the edge off). Assisted dip machine is another option, but again, requires your complete emasculation.
Personally bodyweight dips is warmup enough, but then again, I can comfortably do 6x6 with a 50kg dumbbell between my legs. I've resorted to doing dips after everything else and doing higher reps, as I can't get any heavier than 50kgs at my gym.