Welch's overlapped method for amplitude by frequency estimation
I've found this:
Implementing Welch&#39;s method for Power Spectral Density

That seems to answer the question. However, the author encountered a problem, which I believe may be addressed by modifying the code that was identified as problematic in the thread by:

dataA(istart:iend,j) = data1(istart:iend,j).*window;
dataB(istart:iend,j) = data2(istart:iend,j).*window;