Jim's right, it really isn't that hard to use as long as you have a basic understanding of what it is used for and most importantly, you know the rules. The good thing about the system is that if you don't meet the systems rules, it will tell you before it lets you send any articles to your customers. The tricky part is meeting customer specific rules, I have had some real 'IMDS Tennis' with one particular Tier 1, who kept picking holes in my submission and it took around 5 attempts to have one accepted. The most frustrating thing was that they were being so inconsistent with their assessments. Finding a different issue each time! As long as you have an idea about the rules from your customer, the rest is pretty straightforward, unless of course your product contains a ton of lead or similar, then you've got a whole new issue that is beyond IMDS!
Your biggest challenge will always be 1. Getting the data from the supply chain and then 2. assuring the quality and usability of the data.