In my parish, which has a centrally-located tabernacle east of the altar, the ministers come and stand at the appropriate side of the altar without bowing or genuflecting. They are not passing in front of the Blessed Sacrament at this point, merely approaching the altar on which the Sacrament is placed (and like the rest of the congregation, would have been kneeling, if able to do so, during the period when sacrament is confected).
They do join the entrance procession at the start of Mass and line up in front of the altar. When I genuflect, they all bow, then disperse to their own seats in the nave (no special places, wherever they normally sit).When they have finished their service at communion time, they do line up at the sanctuary step, bow together, and disperse back to their seats. This is the practice I have inherited from my predecessor, which is probably due to the age of many of the ministers.
Liturgically ideal? No. but...
If I require them all to genuflect, some won't be able to do so without pain.
If I require those who can to bow, there will be a disunified mixture of gestures.
If I forbid people who can't genuflect from being Extraordinary Ministers of Holy Communion, I won't have many left to call on!
Bearing in mind the importance which GIRM #42 (2005 E&W edition:
http://www.liturgyoffice.org.uk/Resources/GIRM/Documents/GIRM.pdf) gives to unity of posture, and the guidance of the bishops in wanting the "action of walking solemnly in procession" to be the local sign of reverence to the Blessed Sacrament (Celebrating the Mass #210
http://www.liturgyoffice.org.uk/Resources/GIRM/Documents/CTM.pdf), then (much as I would prefer the simplicity and reverence of both ministers and communicants genuflecting before receiving communion, or at least bowing GIRM Australia #160 prescribes:
http://www.acbc.catholic.org.au/documents/200707031933.pdf) then under our current disciplines, the status quo seems to be the most reasonable option.
FrGareth