Does it still charge to do so?
There is an amount required as a custom anti-spam measure. It is an amount of bitcoin worth like $1.
Perhaps if you ask here for sponsor for some edits that you plan to make, someone will agree to reimburse you for the BitcoinPayment fee after seeing those edits completed.
I was a contributor to the Bitcoin wiki before this obscene rule. My opinion on this is very clear:
As little as 5 bitcents is, I see no reason to pay to volunteer. The only sane reason to pay here would be if you are promoting a product—which is exactly what the wiki needs less of.