Assuming you already have a filter, the D100 is a good candidate for IR imaging. Each successive generation of cameras has delivered stronger filtering of UV and IR light. The D100 has a relatively weak filter on the sensor and with a long exposure you can easily overcome that filter and create IR images.
My guess is in full sun you can look at exposures of 2-4 seconds. It takes a bit of trial and error using the histogram and Manual mode to get the right exposure.
As you know with film, focus is a little different. IR focus is about 10% different than conventional. Using an older lens with the IR mark, you should be able to manually adjust focus as needed.
Newer cameras are less responsive to IR due to stronger filtering. That's why newer cameras are often converted to IR only by removing the anti-aliasing filter and coatings and replacing it with clear glass. Using this approach IR images have similar exposures to conventional imaging.