If the select boxes are displaying related lists (FK), then use "Group By" property in the form field property. Works also in filters.
When lists are very long, it can also work in ajax.
If your combos lists are enums or something custom, then use javascript to show / hide / fill datas ...
The only thing that cook can do to help you is to explode the form.
Choose the config option forms : "exploded"
Regenerate and exract the form tempate. Place this file in your forks.
Change option back to "Condensed".
Hope it helps
