How can I find those marginally attached to the labor force using CPS IPUMS data?
I’m not certain of the definition of “marginally attached workers” you are using. So, in this answer, I’ll assume the definition used by the BLS. These people are defined as persons not in the labor force (LABFORCE==1), who are available for work (WRKOFFER==1), and who have looked for a job sometime in the prior 12 months, but not counted as unemployed because they had not searched for work in the 4 weeks preceding the survey (WNLOOK==001-011).