R help - Oct 2007 - the new package "sets"

Dear Sirs

I can't try the package sets because I have a old mac system. Package 
sets needs R = 2.6. I need to group some variables into a set of new 
variables defined by a particular modality:

Example:

my.df = data.frame(var1=c(1,2,2,1,2,2,1,2), var2=c(2,2,1,1,2,2,1,1), 
var3=c(1,2,2,1,1,1,1,2), var4=c(1,1,1,1,2,1,2,1))

I'm looking for a way to compute set1 and set2?

set1 = c(5,4) % (var1, var2) modality = 2
set2=c(3,2) % (var3, var4) modality = 2

Can you help me, please?

Thanks a lot

jorge