Can't help with Factotum.
Runesmith requires being a Dwarf, Concentration 5 ranks, Craft (Stoneworking) 8 ranks, Armour Proficiency (Heavy), Scribe Scroll, and the ability to cast 1st level arcane spells. They get their rune magic at 1st level, so a single level dip is ok, though Share Runes at 3rd and Permanent Rune at 5th aren't bad abilities.