I personally despise pelt mapping applications. They always seem slower than just automatically unwrapping the object, stitching the seams, then running unfold on them.
What you need to do is this:
1) Unwrap your object
2) Create a "UV Snapshot" from the UV editor
3) Load that snapshot into Photoshop, and paint your texture onto it.
4) Load the painted texture into Maya on a material
5) Assign that material to an object.
*) Whenever you update your texture, open the texture's file node, and click reload. Or you can download this tool: https://www.creativecrash.com/maya/do...fresh-textures
It's also a bad idea to load large psd's into Maya, as they take up an incredible amount of memory. It's best to save a copy of the file as a jpg or tga, each time you make an edit, and let Maya load that.
Hope this helps.
Imagination is more important than knowledge.