1. Create a second log-in on your computer; start up UO in it on one account, switch users, start up UO on the second log-in ID, with the second; switch users as needed to accept & modify the contracts.
2. If you have 2D & KR on your computer.
Start 2D; log in on one account
Then go into the KR directory and start KR with the UOKR.exe file, instead of the normal procedure. Log into the second account.
Set up the rental vendors, then log out of KR.
Note that with both clients running, you will experience EXTREME lag; the only things such dual clienting can be used for is setting up rental vendors, guilding people, and pet rez away from combat. It is also of uncertain legality, but since no one in their right mind would do it for more than a minute, it's not that much of an issue.