Hi Bruce

Please read the Application Note005 an the site www.goalsemi.com

They implemented an 16 tap FIR filter with 40dB stop-band attenuation for 60Hz rezection.
It is used an 12 bit A/D at 480 sps.
Of course the internal MAC is used an there are provisions for even more processing.
I tried to do this job using an 87c552 and I came to the conclusion I can't pass over 10 Hz if I want to avoid the use of a complex external anti-aliasing filter.
Without an MAC I think you can't do something usefull.

Regards,

Cristian