I sometimes go into CT on my SCH and I do make pre-made dungeons for these with Party finder. When the group is about ready to jump in I let them know, "Hey I will be casting lot on X item, does anyone else need it?" If so then I usually say, "Can you please greed roll with me?" If not then just will have to play that class to secure that role.

Most of the time people are always willing to greed. If you make the group, usually people are more obliged to help out.