Tripods, command consoles, and the now-unofficial dual cockpits (from the Mechwarrior Companion) are all working. This will also handle the crew requirements for QuadVees, though there's a lot more to be done to get them functioning. Damage and skills are tracked separately for the two crew members (three in the case of superheavy tripods), and each makes a separate roll to avoid falling damage. If one is incapacitated the other takes over automatically, but without the advantages of having a dedicated pilot/gunner (possibly penalties, depending on the cockpit type). Only the active pilot receives feedback damage from ammo explosions.
What remains now is to add support to MekHQ for assigning crew members and processing units and personnel after a battle. I'm hoping to get to that in the next day or two.
*Summary for those who aren't familiar with the rules for these equipment types:
Tripod 'Mech: Dedicated pilot gives -1 to PSRs (in addition to -1 for Tripod). If another has to pilot, +2 instead. Dedicated gunner does not get a secondary target penalty until the fourth target. If another has to gun, this is lost and weapon attacks are at +2.
Superheavy Tripod 'Mech: as above, plus a technical/tactical officer that gives +2 to any roles to avoid shutdown or ammo explosion due to heat, and +1 (+2 if force commander) to initiative rolls (non-cumulative)
Cockpit command console: One crew member handles piloting/gunning and the other handles command duties. They can switch during the end phase of any turn, or at any time if one is incapacitated. If there is an active commander the force receives +2 initiative (non-cumulative) and does not receive penalties for spotting and firing weapons in the same turn.
Dual cockpit: Dedicated pilot gives -1 on PSRs and superior evasion gives an extra +1 movement penalty to enemy fire if the 'Mech moves at least one hex. Dedicated gunner gets -1 on attack roles, halves penalty for attacker movement (rounded down), gets secondary target penalty starting with the third target, and ignores the first sensor hit. If either is incapacitated the other takes over but loses the advantages and gets a +1 penalty when performing the other crew member's role. The dual cockpit does not exist on any of the units distributed with MM, but it is an option in MML for custom units at the unofficial rules level.