Unfortunately you won't be able to remove the crystal without removing the movement from the case, so no, you can't do it from the front.
Since it would seem you haven't opened a watch before I'd NOT recommend you follow this procedure because with a 7750 movement a lot of things can go wrong if you are not experienced. The sequence would be something like this:
- you will need to remove the caseback
- remove screws/tabs that hold the movement to the case
- remove the stem
- carefully take the movement/dial from the case
- get a low strength glue like a Loctite Threadlocker 222 to glue the numeral back into the dial
- Let it dry under a dust cover making sure dust doesn't get into the case either.
- Reverse the process
The glue alone will cost you (let alone the other tools, gloves, etc.). I'd suggest you find someone that can do it for you.