If you are asking whether you can migrate your historical data from eHealth to UIM, then I am sorry to say there is no good way to do that. CA has stated several times that they aren't going to move that data into UIM. However, I have seen that they created a hook that would let you run a trend report from UIM that reached back into your eHealth db to create a trend line in UIM.
What do you poll in eHealth today? Network devices, systems, etc?? They have been pushing eHealth customers towards Performance Manager and not necessarily UIM. They do focus heavily on the network polling, but often forget that MANY customers use eHealth for system monitoring, too. You can actually do both in UIM, but the PM product is the true network polling product. If you were going to move to PM from eHealth, they did create a migration for that. You have to talk to CA Services for that, though. They won't let you do that on your own.
As for the actual monitoring components, like Phani said it's basically a "start over" scenario. You'll have to evaluate all the features of eHealth that you are using today - Live Health, Time over Threshold, Deviation from Normal, Business Services Console (yes, I said it!!!), and all your various notification and report delivery requirements. Of everything, the reporting requirements are the most challenging. It's just not easy to create reports in UIM. It IS getting easier, and CABI will help a lot, but the learning curve on that can be steep depending on what you need to create.
I am in the middle of this same exercise right now. Well... quite a ways down the road, really. It's an interesting journey.