The ideal would be to link a Rollershutter type Item to a rollershutter type channel. This should work in the same way for numbers, because Rollershutters have a percent state and commands just like Dimmers.
You can present a Rollerhutter on your UI as a slider, instead of default up/down buttons.
You can add transformation features to convert UP/DOWN commands to numbers, or to whatever your device interprets as up/down commands.