most modern faucets have a "quick connector" (flexible hose) between the cold water supply valve under the sink and the faucet. The T just threads between them (make sure to use Teflon plumbers tape on the threads) . If the sink is older it may be hard plumbed in. If it is hard plumbed in I would not recommend this type of installation. I would also not recommend using the connector that punches a hole in the waterline as it is permanent and IMO likely to eventually leak.
It's a new set up we just finished construction on this floor last month. So, I believe we ran the flexible hose from the plumbing up to the faucet. I'll have to look when I get home.
Had a buddy of mine drop some RODI water off for me in the mean time. Should be getting my new unit and new canisters sometime early this week (i hope)