Using vbmakeresid

vbmakeresid creates a 4D residual volume either for all the data in your GLM or for a specified number of time points. It does so by multiplying the stored R matrix (so-called residual forming matrix) by KG (your filtered data). It's a little slow, so residual volumes are usually calculated on-the-fly while the GLM is being solved. But this program will do it too. Here's the help text:

VoxBo vbmakeresid (v1.8.2/Jun  9 2006)
summary:
  produces a residual volume for a GLM directory

usage:
  vbmakeresid  <glm stem> <outfile>
flags:
  -n <num>     number of residuals to collect, evenly spaced if needed
  -h           help
  -v           version