As Tim suggested, I'd recommend checking if Gunnar has a trip available on a date that fits you - as far as I am aware he's the only one doing pelagics in Peru at a regular interval (even though those trips get cancled too, if there are too few people). Doing the whole thing yourself is quite difficult without contacts and unless you speak Spanish.
http://www.kolibriexpeditions.com/birdingperukolibri/perutours/pelagics.asp
If that fails I'd recommend a visit to the Paracas Peninsula, where short trips to Islas Ballestas are sold all over the place in the towns of Pisco and Paracas. Things like Peruvian Pelican, Inca Tern, Guanay Cormorant and Peruvian Booby are virtually guaranteed, while chances for Humboldt Penguin, Red-legged Cormorant and Surf Cinclodes are good. As Islas Ballestas only are some 10-15 km. from the coast truly pelagic species like Albatrosses, Shearwaters and Petrels are uncommon to rare, but the chance is there nevertheless. Of course it should be mentioned that these trips are aimed at "normal tourists", but birds are still plentyful and most are easy to see. Indeed, I am fairly sure there are hundreds of thousands in the colonies on Islas Ballestas and parts of the islands appear virtually all black as they are covered in birds. The nearby Paracas Peninsula is good for various waders and Chilean Flamingo (esp. near the Museum). If you miss the Red-legged Cormorant and the Surf Cinclodes on a visit to Islas Ballestas, the chances are good near La Catedral (a rock-formation on the south side of the Peninsula). With luck Peruvian Thick-knee can be found in some of the fields near the town of Paracas. Supposedly, truly pelagic trips can be arranged via Hotel Paracas, but they are (from what I've heard) quite expensive. Getting "chum" from the fish-marked certainly would be no problem.
