profiling an hp designjet 4500 with the ps driver

hello, does anyone use a colour-managed workflow with an hp designjet 4500 printer using a ps driver? how have you profiled the device - as an RGB or as a CMYK printer? theory says that a ps driver should be able to deal with cmyk directly, but some resources say that a cmyk-to-rgb conversion may ("secretely") happen in the driver and then again an rgb-to-printer's cmyk conversion.
well, yes, I could create both profile types, but I wanted save myself the trouble...maybe someone already knows.
(this is how the workflow I'd use appears: I print form an application supporting CM (adobe acrobat or photoshop mostly), I let the application manage colours and use the appropriate ICC profile (which I created), I disble CM or any colour adjustment in the driver, only select a paper type.)
thanks for replies. jan,