I just added the following write-up to my website. I thought I would add it here so here is a copy and paste version:
Cowl Air Intake
For several years I have had an ARB Safari snorkel as my intake. It just so happens that the cage I am getting ready to build is going to have a tube running up the outside of the A-pillar, right where the snorkel is. So as much as I like having the snorkel, it has to go. That left me with a new problem - what to do for an intake? I didn't want to go back to any intake (stock or cone filter) that gives up the ability to cross deep water. After looking at what several other people did, and concluding that no matter how I tried I would not be able to keep the filter dry if it was inside the engine bay, I decided to relocate the filter to inside the cowl.
The "cowl" is the hollow area between the dash and the engine compartment. Inside the driver-side section of the cowl is where the windshield wiper motor is. The passenger-side section of the cowl is mostly vacant and that is where the HVAC system draws air from. As seen in the photo below with the cowl grill removed, the driver-side is open (for air to enter) but the passenger side is not open on the top (to prevent water from entering right over the HVAC duct).
The passenger-side cowl is an ideal spot for the filter, however to get it in there we need to cut a hole in the top.
Even though a hole was cut in the top, not much water will enter here because the cowl grill does not have any vent holes on that side. You can see the underside of the cowl grill in the photo above. Mine is a 2000 and older models may have vent holes here (I'm not 100% positive). But if that is true in your case you could find a way to seal them off, leaving only vent holes on the driver-side.
Now before going any further, let me give you a parts list of what I used. You may be able to find this stuff cheaper, but I chose the convenient route and bought the main parts at Summit Racing since their warehouse is close by.
item part # cost
Airaid cone filter Simmit AID-700-430 $31.95
3.0" OD exhaust pipe Summit SUM-640030 $12.95
3.0" ID connector Summit WLK-41892 $15.95
3.0" x 30" Spectre flex tube Summit SPE-8741 $25.99
3.0" black ABS pipe Home Depot $5
misc hose fittings and clamps Home Depot ~ $10
I also found this write-up http://www.cardomain.com/ride/325707/7
(thanks Balloo93) which gave me the idea to use the 3.0" exhaust pipe. I found a slip-fit pipe like his but it was only 10" long. I needed about 2 feet which is why I ordered the pipe from Summit. In hindsight I could have saved a lot of money by ordering the 10" slip fit piece and using the full length of the 30" flex tubing, but oh well.
Here is the Airaid cone filter. I chose this filter because of its dimensions. It has a 3 1/2" flange, 4 5/8" base, 3 1/2" top, and is 7" long. It fits just inside the cowl, but it isn't too small of a filter either. I mounted it to a short section of 3.0" (ID) black ABS pipe because this pipe has an outside diameter of 3 1/2". Then added a short section of exhaust pipe for the flex hose to mount to.
Here it is tucked into the cowl.
Here is the flex hose coming through into the engine bay. I used a 3" hole saw for the opening and had to open the hole up a bit more to fit the flex hose through. Also to make room for the tube I had to relocate the under-hood light, relocate the EVAP purge solenoid, and move the large loom of wires out of the way. It was not hard.
And here is the rest of it going to the throttle body. As indicated by Balloo's write-up, the diameter of the exhaust coupler I used is exactly what you need to attach the stock "accordian" throttle body tube. I welded the coupler in place but it was such a tight fit I think it would have been just fine without welding it. I also plumbed the CCV tube like in Balloo's write-up.
I was told by a friend who also had his intake set up this way that it might be loud inside the cab. He was right! When I first started the engine I was shocked at how loud the sucking sound was coming through the vents. After a few seconds the sound diminishes to where you can barely hear it, but I was still concerned that the sound might be an annoyance. Well after driving on the highway and on a trail ride, I had completely forgotten about the sound and didn't notice it at all. For the person who is overly concerned with noise in the cab, this modification might not be right for you. As far as any "performance" gain, I didn't notice any increase or decrease, but I wasn't expecting any either. As side benefits to this modification, I am still sucking cold air and I can get rid of the stock airbox, creating more room in the engine bay. Overall I am very happy with this modification.