The sentence can mean either but it would be much more obvious in spoken English. If you emphasize 'you' then it's clear that the speaker wants the person they're talking to to tell Jim and not have Oliver tell Jim: Would YOU tell it to Jim instead of Oliver? If the emphasis in spoken conversation is on 'instead' it would mean they they want the person they're speaking with to tell Jim and not to tell Oliver Would you tell it to Jim INSTEAD of Oliver? In written English you'll have to adjust the sentences unless you're certain the context is clear. A simple comma won't really do it. "I'd like you to tell Jim, so Oliver doesn't have to" or "I'd like you to tell Jim. I don't want Oliver to do it." For the other meaning: "I'd like you to tell Jim but not Oliver" or "Don't tell Oliver but please do tell Jim" or simply "Tell Jim, not Oliver"

Written, there's no difference. You could mean either "tell Jim and don't tell Oliver" or "would you tell Jim, so Oliver doesn't have to." It's perfectly correct for both.