Hi Everett,

ET> ...so hatthinaago... yena Bhagavaa ten' upasankami; upasankamitvaa
ET> pana Bhagavanta.m vanditvaa olokento añña.m kiñci adisvaa
ET> bhaddasaalamuula.m paadena paharanto tacchetvaa so.n.daaya saakha.m
ET> gahetvaa sammajji.

ET> My first try, loosely: that elephant, approached the Blessed One,
ET> however having approached the Blessed One and saluted him, looking
ET> around (and) not seeing anyone else, (he) trampled the (area around
ET> the) root of the magnificent Sal-tree and prepared it, (then) taking
ET> a branch with his trunk, swept (the area).

I agree with your translation and interpretation.

ET> This seems to partly support Burlingame's reading, that the chips
ET> flew and wood was broken by the elephant's pounding feet. Does anyone
ET> have know of any parallels in other stories, or know any traditions
ET> concerning living at the roots of trees that would help make sense of
ET> this?

There are many mentions of monks sitting at the root of the tree in
the suttas:
http://www.accesstoinsight.org/canon/majjhima/mn018.html
http://www.accesstoinsight.org/canon/majjhima/mn066.html
etc.

ET> Or has anyone seen 'taccheti' in a more general sense, 'making,
ET> preparing, ordering'?

At least 'tacchati' has such meaning, see 'magga-tacchaka' -
'road-builder'.

Best wishes,
Dimitry