You have 3 options:
- Convince one of the existing ZAP developers that they should implement it
- Convince someone else to implement it for you
- Implement it yourself
Some of the ZAP core developers are paid to work on ZAP. If you can convince one of the us that we should implement it asap then this will probably be the quickest option as obviously we know the code base well. However we are all very busy and the companies who pay us have expectations on what we will deliver. We do have a lot of freedom to do what we think is right, but we all have a long list of things we'd really like to work on. But it doesn't hurt to try.
Failing that you can try to convince someone else to implement it for you. The ZAP Developer Group is a good place to find people interested in working on ZAP. The Bounty Source site allows you to put bounties on ZAP features, so that might be a suitable incentive for someone.
And the final option is to implement it yourself.
We, the ZAP core team, will do our best to support anyone who wants to contribute to ZAP. We often spend more time helping other people implement a feature than it would take us to implement it ourselves. We do this because we want to encourage people to get involved in ZAP, and we think it's a good investment in our time. It doesn't matter to us why people want to get involved - if it's just because someone else is paying them then that's fine.