How would you manually enter users UID on account creation?

I have been using drupal for a while and when i was on 4.6, I needed to customize alot of things. Because I was stubborn, I didn't want to relearn the wheel on how drupal does forms, etc etc..so I created a custom script that we used to create users. The main reason was the lack of an obvious means of entering a custom UID for the user. We use drupal to distribute a financial newsletter and did not like the default UID being so low.( im just the dev guy, dont ask me ;) ) We created the admin account using the default 1 and 0 for anon, for subscribers we started at 102001 for the uid.

Now my problem.

I am currently porting everything over to drupal 5.1, removing all of my clunky workaround scripts. I am almost 100% complete with exception on what to do about the custom UID fiasco. I have several hundred subscribers from old site with correct UID's, but if i add a new user on the 5.1 version, it starts at the lowest available # (ex. uid = 3 ). I know thats the defaut behavior, but I want to change it.

Now my question.

Is there an easy way to code in what drupal uses as the UID when creating an account? Ideally, because users cant create their own account, we would like to just have a simple box above the username on the registration form where we can manualy insert the UID that we chose.

Thanks in advance for any clues.