If you are an R user, the SNPRelate package provides PCA and routines that would allow you to bring in datasets like 1000G from VCF or PLINK format files: http://corearray.sourceforge.net/tutorials/SNPRelate/#principal-component-analysis-pca http://dx.doi.org/10.1093/bioinformatics/bts606

I never got to play with it, but kept it saved in my to do list (probably forever): http://alimanfoo.github.io/2015/09/28/fast-pca.html

If your data is in VCF format, you can do this with peddy: https://github.com/brentp/peddy

The command would look like:

python -m peddy -p 4 --plot --prefix my.out $vcf $ped

this will do a PCA with your samples projected onto those from thousand genomes and ancestry predicted according to those. In addition to an interactive html file, you'll get (among others) a PCA plot that looks like:

Where the points from your cohort will be the big open circles and the small ones in the background are the 1000 genomes samples.