This is one of the many reasons why I keep a copy of 9.3.1 on at least one PC. If it ain't broke . . .
The functionality has indeed disappeared from inside the geometric network wizard. ESRI now recommends that you fix all snapping issues before building the geometric network. It's quite a bit more complicated but it can be done.
If your data requires a lot of changes to ensure coincidence, consider first creating a Topology on your data to find and fix the errors. Topology contains an exhaustive set of rules to check for data integrity violations and a suite of tools and commands to correct any errors. Creating your geometric network prior to correcting spatial and attribute errors can often lead to more work when correcting the errors. Because network features have special behavior and are aware of what they are connected to, correcting issues such as overshoots and undershoots can take more steps and time once the geometric network is in place. For this reason, we recommend that building your geometric network be done after correcting spatial errors.