In addition to the above,,you'll also need to modify the receiver. The ejector guns use a different mainspring follower. The end is longer,,split and spring tempered to hold a small, thin sliding blade in front. The receiver is bored through from the front of the knuckle into each mainspring cavity to allow those 'blades' to protrude & trip the ejectors when fired. The holes are also counter bored and a small bushing with opposing slots in it is inserted and holds the blade shape inplace from the front.
Yes it can and has been done. Most anything can be done. Lots of work and fitting. Might have to spot anneal the receiver to work on it.
Those holes will be going through the hinge pin, so if the gun is loose at all, go ahead and re-pin it before you start.
Like bbman3 says, getting the ejector forend parts will be the most difficult part. Labor involved can run up the cost of the project very quickly.
I know that Pete Mazur has done these conversions in the past. Don't know what the cost would be.
