First I would guess you mean Cat5E as Cat5 is no longer used.
Second. are you talking about the Manufacturer WireMold and it's products or are you just using wiremold as a generic term? The correct term is Surface Mounted Raceway.
The best place to find your answer in in the data sheet or specifications for the raceway you intend to use.
There is no capacity limit for data cable in any type of raceway according to the NEC (the best that I can remember), but many manufactures recommend no more than 40% capacity.