I use cones and splurged on an adapter for a whopping $5 (I bought mine decades ago so it was probably only $4 when I got it)
http://www.walmart.com/ip/24548339?w...801872&veh=sem
I would, however, advise against using serger thread for piecing. Serger thread is notoriously weak as it is not meant to be used as the only thread in a seam but serged with multiple strands.
LOL Geri B we were posting at the same time! Great minds think alike