Seems like it could be a long shot in large organizations. The managers close enough to you to be on your side don't have enough clout to override HR responding with "we don't make changes to employee contracts", and the ones who do aren't in touch with the craft enough to understand why you'd want such an exception.
I have successfully gotten a clause like this changed or adjusted in a large corporation twice. Both times I signed first, then raised an issue in an email which was intended to be forwarded to the lawyers. My email included specific, detailed objections ("as written, this means that the company owns the bedtime stories I make up for my children") and proposed alternate language ("We could, for instance, replace the clause 'all intellectual property' with 'all intellectual property related to the company's business or produced using company resources'.").
In one case, an international company with a couple-thousand employees in the US, the company lawyers never got back to me, but the next year the contract was changed and it included a variation of my original proposed language. In the other case, a US company with tens of thousands of employees, the company lawyers got back to me immediately with a statement about how they intended the existing language to be interpreted (and this addressed my concerns).
I can't promise you will get the same results, but I thought it was worth sharing my anecdotes.
That was the first objection they raised. I pointed out gramatical issues and other flaws in the contract that made them have to send it back to the lawyer anyways, and it came back w/o that clause.
