To my knowledge you can not register it directly.
What I do is, after the wedding date entry I enter
the signs
o|o xx.xx.xxxx (and the date of the divorce)
The pictures of the tree printout will now show the information.
Everything else I always write into the notes.
Another possibility is to give two years:
FROM 1990 TO 2000
or
BET 1990 AND 2000
Though this is not recommended in the Gedcom-Standard (as isn't the "o|o"-Solution). Ahnenblatt will export both solutions correct, but you don't know what the importing software will do until you test it.
Marcus