Creating RPM for altera devices

Not exactly. Incremental compilation can be used to lock down placement(and routing if you want), but can't be stamped out onto different locations. A design can be back-annotated, whereby the logic will get specific X/Y locations, which could be modified into relative placements, but it is not trivial. Both of these will lock the logic down to exact locations.

If you want the whole block to "float", you can do a floating LogicLock region, but the exact locations inside won't be locked.

To be honest, floating LLRs are not a great thing for placement(and they're less restrictive than RPMs, so RPMs would only be worse). It is difficult for placers to move large groups of logic, since they dislocate so much other logic and hence any movements are very distruptive. It's like trying to fill a jar with rocks, but only having large stones instead of small pebbles.

Finally, I would make sure you need it. It's a nice comfort factor, but the fitter does a very good job of placing things. And when it doesn't, it's usually because other factors affect that, which wouldn't be resolved by an RPM. I used to do some of those(back in the XC4000 days), but really haven't found a need with Altera devices.