Making a hex grid with Gimp???

[derio]

I can't find a "real" way.. but one way to fake it is to use the Filters->Distort->Mosaic and pick the hex. You have to do this on a color layer.

Size =?
Height= 1
Spacing = 1 (or whatever you want the line thickness to be)
Neatness = 1
Light = 160
Color = 0

Run and then use the select by color tool to select the inside color of the hexes and delete to alpha. Invert selection and fill with black (or whatever color you want the grid)

I'm trying to modify some existing maps I have from some old role-playing games by over-laying a hex grid on top of them. I found this by searching the archives and it does pretty much what I'm looking for, except for one big problem: the Filters->Distort->Mosaic filter in GIMP can only go up to a size of 100 pixels, and I'm needing a much larger size due to the high resolution of the original map I'm overlaying a grid on. Is there any way to override or work around this limitation?