Some of this info can be found in bits on pieces on this forum but here is a complete guide to making digital scratch records including skip-less and Y records in your DAW for serato.

from the article:
"There are no magic tricks up Q-Bert’s sleeve; a scratch record is just a record — a series of samples recorded linearly on a record. The trick is just in how the samples are placed on the record. The speed of the drum loops and the spacing of the samples can create very helpful characteristics that make a crazy scratch sequence easier to execute. You may have heard people throw around terms such as “skipless records” or “Y record.” Those are common techniques used for creatively spacing samples around a record, which you can recreate in your DAW."

full article www.djtechtools.com