Part of this is going to rely on which books you're using. Spell Compendium offers a great deal of help, but not everyone uses it. There are many more SR: No Conjurations (although PHB has a couple, Melf's Acid Arrow comes to mind) , which the sorcerer could use in a wand or off a scroll even if he doesn't know them.
Magic Circle Against Law would be your best friend about now. Centered on your sorcerer, it'd prevent him from being actively dominated (though he could still be targeted for the domination), and if he gets within 10 feet of his buddies, it's officially up to your DM to determine what happens -- they may all regain their senses. Even if they don't, I'd ask whether they now count as allies; if so, any dimension door/teleport/plane shift/regroup attempt should work.
SpC offers assay spell resistance at level 4 (which your sorcerer would also be able to read off a scroll) and that grants +10 to the SR check against one individual opponent. In your situation, it seems pretty easy which opponent that would be. All of the orb of ___ and lesser orb of ___ spells will do decent damage and bypass the formian's SR.
Magic Item Compendium offers items that boost your SR level checks as well.
If you're going to go the route of hiring NPCs, try to find a Marshal with awesome Charisma and Determined Caster as a minor aura. That should give you anywhere from +4 to your check and up (and boostable if you give said marshal a Charisma-boosting item or Eagle's Splendor).