[BioC] filtering for present calls

[Garcia, Joshua A]

I am using the gcrma package in R to analyze affymetrix HGu133A chips and 
would like to normalize only the probes called present by GCOS.  I can 
separate the probes called present from the rest by using the chp file 
exported to excel, however, I would need to recreate it as a .cel file for use 
in R.  Is it possible to do this?  Is it possible to use an excel file in R, 
rather than a .cel file?  Any suggestions?  Any help would be much 
appreciated.

Thanks,
Josh