I would like to merge a GEO data set with my own idat files for analysis. Does anyone know how I can go about doing this (RnBeads would be preferable, but ChAMP or minfi would also be fine)?
I'm not sure if this covers your problem, since you introduced it sparsely. But you might be interested to first bring both data to the same reference system before merging, see software for it: http://trac.osgeo.org/proj/
If still the locations of your data are not the same as with the GEO data, you might use the over() function from R package sp.