Assigning US IPs to foreign traffic

My question:

Is it possible, on a dedicated server, to automatically assign a US IP address to a user logging on from a foreign (non US) country?

Example: a user logs on to a site from Romania, with a Romanian IP address. But open entry, his Romanian IP address is over-written by a US IP.

If this can be done, and you can do it, please contact me for the job.

Thanks,

CE