Is there a way to increase the caster level of a magic item, either temporarily or permanently?
I was looking at the Shawl of Shadowy Disguise from Blood of Shadows, which states, "While worn, the wearer can hide her appearance as if with a penumbral disguise spell." The spell Penumbral Disguise reads, "You mask your features with shadowy illumination, gaining a competence bonus equal to your caster level on Disguise checks and Stealth checks attempted while in normal light, dim light, or darkness."
Now, I gather that the primary point of the cloak is the spell's OTHER benefit (obscuring your features when not in bright or normal light), and not the skill bonuses I listed above. But so far as I can tell, those bonuses would still be applied, albeit at a relatively low bonus since the cloak's caster level is only 5. So, that got me wondering if there was a way to pump up the cloak's CL.
Thoughts? Even if I've read the cloak's rules incorrectly I'd still be interested in learning whether a magic item's CL can be increased after creation.