After asking Neteller Support they confirmed that a manual transaction can not be reversed.
No, Virwox no longer supports Neteller and I would advise highly against their service. The lack of transparency from their side is absurd, they take single side complaints and reverse transactions (all of them), to add injury to the pain, they will froze your account meanwhile. Neteller Support is the most stupid system in the web, they have no clue about nothing and the answer they gave you seconds this up.
Summing it up, Neteller as a service is a scam. If you intend to use this sort of services, and even if the risk is equally very high, try Skrill.