I am interested in becoming a reseller and would like to know how to transfer domains into my service. I realize that purchasing domains can be done with a script, but what about transferring?

It should be possible to do with a script... but it depends on the registrar you are reselling for. Which one did you choose ?

I haven't decided what company to use. Does anyone have any good ideas?

Try eNom...

Get a reseller account and you will see if it works for you. Most people (including me) can set you up with a free $8.95 reseller account...

Good luck with your search !