The PicoCalc is now supported by OOTB (out of the box) PicoMite and WebMite.
see PicoMite/WebMite V6.02.01 release candidates now available on TBS
The latest Release Candidate 2 can be found in the post: https://www.thebackshed.com/forum/ViewTopic.php?FID=16&TID=18703&LastEntry=Y#251881#251862
It is recommended to nuke the flash before installing the version from TBS forum, subsequent installs do not need to be nuked unless the Peter Mather states otherwise.
Until now my latest bios v1.6 is available on: http://raspi1.mypi.co/download