People do do DIY cost segregation. For what that's worth... And just to say this, I know CPAs who will do their own cost segregation studies using software like you reference. (FYI I'm not doing this... but friends are.)
BTW, I'd think if you were going DIY route that you should have your tax return prepared by a tax accountant who really knows real estate. Someone new to the real estate professional rules (which are complicated)... doing a cost segregation (which is basically a civil engineering task)... trying to self-prepare a return that looks clean and audit-flag-free? That seems pretty risky.
P.S. We've got a bunch of real estate related blog posts including lots of info about the "real estate professional" loophole at tour blog:
https://evergreensmallbusiness.com/category/real-estate/