Let's deal with the 'easy' part first: hiring someone for ~100 hours of consulting.
How easy or difficult this will be is going to be based on what answers you need to the questions "When can you start?" and "For how many hours are you available per week?" If you need them to be available during set hours, this will also effect the situation.
When can you start?
Most busy/qualified/established professionals book their time out in advance, very often 3-6 months out or more. I'm not some super-in-demand expert or a professor, and yet I've turned down four offers in the last few months because I have already dedicated myself to things that would make my first availability to be summer of next year - unless it was just an amazing offer with triple the money, at which point I'd still only be available a fraction of the time for the next 3+ months.
Especially with teaching, grants, budgets, and research schedules, finding someone who could dedicate more than a few hours a week within 3-12 months will not be common.
If you only need someone for a few hours a week spread out over the next 3-4 months, you will likely have a much easier time of finding someone who is at least available and potentially interested.
Sabbaticals, Summers, Internships, and Finding the Time
If the initial stages go well and you need hundreds of hours of consulting or extensive research, this will not fit into the schedule of a professor under normal circumstances. It's not to say it can't be done, but if the person is really interested - both by the project and by how much money they stand to make - there are a few ways to make it work.
One way is for academics who have flexibility in the summer. While senior faculty will often direct labs, summer research, and some even have teaching duties 4-5 days a week over the summer, there is still often more time that can be squeezed out for consulting than other times. If this has been arranged a year in advance, or if the person happens to have already arranged for a light/no summer load, they would potentially be available for consulting for this larger work load.
Once you start needing more than 20-40 hours a week of consulting, it is reasonable to start considering having more than one person. It would not be unheard of for a professor - especially in fields that are highly tied to industry like in technology/computer fields - to arrange for a summer internship/research project where they and their hand-chosen grad students might be available to do work.
This sort of arrangement would allow sufficient time and expertise, and allow a faculty member to get a sufficient return for their invested time - teaching, helping students, conducting applied research/work, and bringing in some extra personal wealth.
Approach a Prospect and Be Open, Honest, and Straightforward
You have a situation where the industry lags behind the state of the art research, and you feel you have a great financial opportunity if you can close the gap - and need an expert to help you do it. That's great!
Professors and researchers are humans too, and are interested in things like making money (especially when it brings the potential for even more money), working on interesting problems, etc. If it is applying existing knowledge/research to a problem it might not result in interesting research, but this is very field-dependent as case-studies and applied techniques are standard in some fields and unpublishable in others.
Most people who have any experience in industry also understand the funding cycles are surprisingly similar to academics - you have a little bit of funding available to invest into exploration, and what happens from there depends on the results you get. So be open about this - if you know you have budget and money to pay them for the exploration phase, say so. If that phase doesn't work out then it will mean you don't expect to have any more immediate work - say so. And if it works out and you get the funding you are shooting for and will need a lot more work done - again, just say so.
Start a conversation and see where it leads. As with most professional tasks, it is not uncommon to have an offer come across your desk that just isn't something you are interested in, but perhaps you know someone who you might refer the opportunity to. Perhaps you'll find the professor who wrote the papers that attracted you to them in the first place will say that they actually don't feel they are the expert, and that actually the student they were working with would be better able to help you. Maybe they'll insist they are a package deal - you hire them and their collaborator. Perhaps they just aren't interested. Perhaps they already had a sabbatical planned and haven't 100% decided what they wanted to do, but this would fit the bill nicely...etc.
With a clear plan, seed funding in hand, and an open and honest discussion about your situation, goals, and what you can offer, most professors will be happy to take a meeting with you and discuss the matter! Few people are so busy as not to be able to talk about extra money, and most higher-level professors reserve a portion of their schedule for consulting gigs anyway (again though, this varies by field).