Here's the problem. The 7290 is slightly deeper than the 7230, so it becomes a tighter fit for the standard-issue RIM leather case. Add egrips, and it becomes very difficult to insert or remove the 7290 from the case.
The solution? Install the egrips but leave off the large piece that goes on the back. Then stretch out the leather case to accommodate the larger Blackberry. I used my old egrip-equipped (say that five times real fast) 7230 with a thick piece of cardboard wedged between the screen and the leather case.
Handy Dandy Case Stretching Tool
After several days of stretching, my semi-egrip-equipped 7290 slides in and out with only a minimum amount of resistance.
Newly Expanded Leather Case
Of course, now it's way too big for a 7230 without egrips. For our next project, we'll spray the stretched case with water, place it in a dryer, and check to see if it goes back to the original shape.