If it is not so problematic I think it is better to change the chip with a dual touch version (if 4 wires touchscreen used on N900 is compatible) and then set it on singletouch mode.
I don't remember the name of that chip but it is present on 2010-2011 posts.

Nothing will initially change but we have a door opened for the future.
Instead a real dual touch with N900 original chip is not possible (otherwise we already have it on N900, with specific application, without waiting Neo900).

I.e. Kobo e-book readers have a infrared touchscreen which is dual-touch capable but Kobo uses it only on single touch mode (mode is changed at kernel level, and it is also possible to enable a parallel singletouch + dualtouch mode).
Probably because they not have a dual touch driver, driver for input events not for chip itself, for their linux image.
Sony has written the driver and with same hw has dual touch capabilities.