Is the 2000 Toyota 4runner equipped to handle a child safety seat with the latch system?

Sort of. You can retrofit a tether bracket, but not the lower anchors. See: http://www.saferidenews.com/pdfs/new_page_pdf/TM_LATCH_update702.pdf It's part number 73709-12010 for the tether bracket - they run about $12. The old part was 04731-22012 and includes the belt tightener "I" but no tether bracket.

There are people who have retrofitted the lower anchors by drilling holes and mounting brackets from other vehicles, including late 90's model Honda Civics. I wouldn't personally recommend that.