I was going to suggest my $10 solution until you mentioned that you use a MacBook. My software is Windows based.
Canon Raw OR TIFF files from scanner
LR/Enfuse exposure and focus stacking
Microsoft ICE stitching & TIFF output
Back to Lightroom for final tweaking
For pure HDR processing, OLONEO Photo Engine worked nicely when I had the early beta/test version. I haven't purchased the commercial product.