It's a little clunky at the moment, but you should be able to use creative modules - create a "custom module requestor" item (the gray one), right-click it and drop the creative module you want to request into the item slot. Note that you'll need to open the config dialog every time you want to change which of the modules you're requesting, I've requested an API feature to let multiple copies of the custom module tool be configured for different modules but it's not possible just yet - https://forums.factorio.com/viewtopic.php?f=28&t=61498
