There are several ways to do it.
The easiest is to simply call the guest on the phone and take two manual payments over the phone. To do that, follow these steps...
1) Create a manual booking by finalizing their quote and turning it into a booking
2) On the new booking, go to the Payments tab and click "Collect a New Payment"
3) Call the guest and, with them on the phone, enter their credit card info for the first payment and then do it again for a second payment. Make sure to set the payment amount on each one to what they want charged for that card
4) If there is a balance left after the two payments, schedule a payment to be collected for some time in the future according to your normal business workflow
5) Go to the Security Deposit tab and schedule a security deposit to be collected according to your normal business workflow
6) Go to the Legal tab and make sure to send them a renter agreement to sign
Ordinarily, the system would set up the scheduled payments and security deposits for the future when the guest completes the quote acceptance form online. In this case, since you're doing it manually, you need to make sure that's done.
The other way you could do it is to adjust their quote to have a fixed amount for the first payment. Send them the quote and let them submit their payment online the normal way. Then, go into the system and collect a manual payment for the second payment with them on the phone.
Hope this helps,