Open up either choice, and retrieve the 'materials' folder from it, placing it in your 

steamapps\team fortress 2\tf\ ~ folder. 

It should ask to replace if you've got any other custom skins installed.

Default Quality - Compressed Color Textures with 512x512 Normal Maps, as is TF2's defaults. Only new thing is a custom bumpmap for the BLU spy hand, as it is slightly different.
High Quality - Uncompressed (Large file size, less color loss) Textures with 1024x1024 Custom Made from scratch normal maps to accompany the default texture dimensions.

This is version 1. Subject to change.

Credits go to Brendan "Mescool" of FPSBanana, for the base texture of the exposed spy hand from his "No-Gloves Skin" Spy hand.
Normal maps created from scratch by me.

-Mao