Metamagic feats can be used when creating magic items
Magic Item Creation says, in part, that
While item creation costs are handled in detail below, note that normally the two primary factors are the caster level of the creator and the level of the spell or spells put into the item. A creator can create an item at a lower caster level than her own, but never lower than the minimum level needed to cast the needed spell. Using metamagic feats, a caster can place spells in items at a higher level than normal.
Emphasis mine. Thus, for example, with the GM's permission a character can create an amulet of empowered fireball.
The GM determines a custom item's price and requirements
Magic Item Gold Piece Values says, in part, that
The correct way to price an item is by comparing its abilities to similar items..., and only if there are no similar items should you use the pricing formulas to determine an approximate price for the item. If you discover a loophole that allows an item to have an ability for a much lower price than is given for a comparable item, the GM should require using the price of the item, as that is the standard cost for such an effect. Most of these loopholes stem from trying to get unlimited uses per day of a spell effect from the "command word" or "use-activated or continuous" lines of Table: Estimating Magic Item Gold Piece Values.
Emphasis mine. Further, since any new magic item must meet with GM approval, the GM also determines the item's construction requirements, which could certainly include, for example, the feat Empower Spell for an amulet of empowered fireball. Note, however, that, instead of as a requirement the spell empowered fireball, the requirement would more likely be, separately, the metamagic feat Empower Spell and the spell fireball (cf. incense of meditation, book of extended summoning, robe of gates). Further, the GM could add as a requirement a minimum caster level (in this case, perhaps, 9th or 10th) to represent a caster's ability to prepare such a spell. (A magic item's caster level is the usual level at which it's created rather than a construction requirement, construction requirements being listed separately. For an example see the Construction Requirements and, on the same page, a FAQ here.)
This means such requirements can be waived by increasing the Spellcraft skill check necessary to create the item by +5 each.
(In the example of an amulet of empowered maximized disintegrate, the effect generated would usually occupy a typically impossible 11th-level spell slot. Luckily, because of the way requirements usually work, a character typically only needs to be able to cast the spell disintegrate and only needs to possess the feats Empower Spell and Maximize Spell to create the item, not actually be able to cast an empowered maximized disintegrate spell. It's possible that the metamagic feats Silent Spell and Still Spell wouldn't do such an item any good, but the GM may rule that the combination allows the item to be used as a purely mental action, so that, for example, the amulet could be employed by a paralyzed wearer.)
