I would start pumping and putting it into a bottle and then gradually start putting formula in as well. Little by little your baby will become used to the taste of the formula until they are completely weaned off the breastmilk.
why? you have come this far so why stop now?
Why would you want to? I nursed my children for 3 years, they didn't get sick and their poop didn't make me gag like formual fed babies does. It costs a lot of money to purchase formula and a lot of time to make it up, wash the bottles, wash the nipples, replace the bottles and nipples and so on. If it ain't broke ... don't fix it. *grin*
Listen to Deanne -- alternatively, listen to the _thousands_ of previous Q&A on here about what happens after this sort of 'told to do 2 ounces of formula.' Hi, my baby is constipated and nothing is helping. Hi, my baby has reflux and cries every time she spits up. Hi, my baby has had a cold for two months and the doctors can't do anything. Hi, nothing works to soothe my baby, help. Etc etc. You're nursing now, you have the milk available -- make with the milk.
My daughter was 7 weeks old and still exclusively breastfeeding when it was brought to my attention by some well-meaning people that she should already be used to being bottlefed, even if only part time while I still breastfed. I panicked for a while because she wouldn't accept anything but the breast. Then I realized that I hadn't been having problems exclusively breastfeeding her, so I gave up trying anything else.
It's only going to be a couple of months before your baby will be starting solid food, and will be able to go much longer between feedings. Around that time, you can probably give formula in a sippy cup too, since your baby will be more developmentally ready to try out new tastes and new feeding methods.