For under 100m (300') I'd tend to go 10Base2 (thin net) coax - easier to cable AFAIC, using RG58 A/U or C/U coax. 10BaseT cable should be Level 3 or better; runs approaching or exceeding 100' should use Level 4 UTP cable such as Anixter CM-0042BAG-4. I believe that 3COM sells crossover cables made with this; any good electronic supply house (I use Pilgrim Electronics in Danbury, CT) should be able to make cables to length for you. If you want to make your own crossover 10BaseT cables, you have to exchange the RX and TX pairs as follows:


6---2
3---1
2---6
1---3

Looking at the front of the male RJ-45 connector, with the pins facing down, pins are numbered 1-8 from left to right.

Ed