I’ve had 2 stress fractures this year so have spent a ton of time cross training. I’m no expert by any means but what I do is essentially try to mimic a running week. Example:
M-elliptical 60-90 minutes keeping hr similar to what your easy pace is
T: Bike workout- 12x3 minutes w/1 min rest, 6x6 mins with 1 min rest. 15-25x1 min w/30 seconds rest. Basically mimic any workout you would be doing by time.
W- same as monday
Thu- same as Tuesday
Fri- Same as Monday
Sat- same as T/Th
Sun- 90-120 minutes on the elliptical or 2-3 hours on the bike. Usually keep this fairly easy to mimic the long run.
i like to do my workout days on the bike but can absolutely use the elliptical too. As far as strength goes pretty much the same as you normally would but obviously stay away from loading the affected area.
Hope this helps but of course others may have different or better suggestions. Good luck!