Does anyone know if the programming guide for a 28i is the same as "124i/384i software manual"? I couldn't find one on the web site that was specific to a 28I.
Any ideas?

for the most part yes.
if you have an older 124i then some programs have changed slightly but follows the 384i

28i has commonized software. Newer 124is have the same. they commonized it to match the 384 and 704 series.

99% of all programming will be the same aqcross the board