@Sophil & Peter <de>: Wow, guys, that's really touching. What it is to feel one has at long last made a difference in the world... (-;
But seriously, I agree with everyone else that 'to olden' probably doesn't need to be in LEO, or at the very least should be marked [obs.]
My OED (offline, print, 1991 rpt. 2002) marks the entire verb sense as /rare/; the latest citation for 1. intr. is 1852, for 2. trans. 1863. (And BTW Thackeray predominates in the whole handful of citations -- maybe no one else used it all that much even back then?)
And I can't actually believe the OED online version is serious about trying to resurrect the word on the sole basis (apparently) of that one 1994 citation quoting a 100-year-old lady in Virginia. Even there, the word is clearly put in quotation marks to indicate that it's amusing, not normal English; the woman could have been senile for all we know, or had a quirky sense of humor and made up the word on the spot, or been the last living representative of some obscure Appalachian speech pattern, as the rather backwoodsy 'olden up' might suggest. (Or the last living Thackeray groupie, come to that...)
I did try a web search just in case. 'Oldened' turned up a surprising 1540 hits, but on closer inspection, all of them after about the first 30 were just lists of random words. Of the rest, after I discounted all the ones from sites in other countries, the people writing *'oldened days' instead of 'olden days,' and the 19th-c. lit. (well, okay, Hardy as well), there were only 5 (five) left, all IMO garbage. The hits for 'oldening' were similarly spurious; the few pieces of real text were mostly either obvious errors or lame attempts at humorous or creative coinages, and the pages of random word lists began at about 20 out of 1890.