Satellite - bootstraping client without major package upgrade ?

Hi,

I am going to register a few hundreds of RH servers to our internal Satellite.
So far I did just test / dev hosts using bootstrap script and all went well.
The next long list of servers is the production one. For obvious reason
I don't want them to install any other package that needed to register to Satellite.
Some of them are really old (RH 4.* / 5.*, etc) so I am afraid that on some of them
it might be that rhncfg* packages being installed require kernel upgrade (or any another
core package ...). Can anybody suggest any way to verify that installing rhncfg* packages
won't involve any major package change ?

Regards
Przemek