...If I were going to use the hue/sat method and was looking to change it to a specific color...say #70cca6, how would I go about that?
We get this sort of request (ie, for a specific "color") with some regularity, here on PSG. Unfortunately, I have a problem with the way it is phrased. Specifically, the hex value for a "color" specifies the R, the G, and the B values for the "color". So, if one were to make some relatively uniformly colored area of the shirt the HEX "color", in the area you changed, you would lose all texture, shadowing, changes in saturation from point to point, etc. That area would look more like a paint sample card with completely uniform color and brightness, not anyone's shirt.
I think that what you are really asking for is to change the hue of that area to a different hue, but leave the luminosity (brightness) information alone. However, once we start talking in HSB terms, not RGB numbers, we also have to think explicitly about how we want to handle point-to-point variations in saturation. These variations help make the texture look real, particularly, in the shadow and highlight areas.
For example, if one puts a Hue/Saturation adjustment layer above the part of the image that needs to be changed, and one does what I suggested (ie, move only the hue slider), then the point-to-point variation in the saturation and luminosity will be identical to what one has in the original image. In contrast, if one clicks the "colorize" box in the Hue/Sat adjustment layer, then the only information preserved from the original will be the luminosity.
Sometimes, the first approach is better, particularly if you are starting with an area that is neither very bright, nor very dim. Sometimes the 2nd (ie, "colorize") is better, especially when one is dealing with very bright or dark areas.
The bottom line, however, is that using either of these approaches, you'll wind up with hardly any pixels that have the exact same RGB hex code as you specified, but the new colors will have the hue (and possibly the same saturation) specified by the Hex code.
Just a thought,
Tom M