Is it possible to locate a person's ip address from their myspace id # and/or name, and if so.. how do I do this?

Nope

No, it is not possible.

Simple reason.

IP addresses are basically an address for your computer. Every computer's is different. Myspace ID's are NOT unique. I mean, just search for "tom" on myspace, and you get thousands of results.

EXAMPLE:
I create a myspace on my computer.
I change to a custom id at my friends house.
I change my screenname at the local library.

How could any of that be linked to an IP address, when it could be done from any computer?

Find a better explanation of IP addresses, and a fun little IP address recorder toy, at THIS SITE.

Yea I agree with everyone else. Just for kicks and giggles can I ask why u want to know? It kind of sounds "creepy"

It's called privacy dude, if people can find out who you are by the accounts you open up online then there's about 5 people on eBay I would like to know where they're located. :D