snmp_send_async() for v3 PDU

hi all.
I've seached on archives but couldn't find any awnser for my question.
Here it is:

I'm building a tool to discover agent's version (1, 2c or 3), starting
from 3 to 1. It simply does a GET on a well known OID (like a ping).

As I have lots of agents to query, it whould be nice if my tool sends
various GET PDUs at once and waits for some replies. This works fine
for 1 and 2c, but if my PDU is v3, snmp_send() or snmp_async_send()
blocks until it timeouts (for non-3v enabled agents).

My question (finally) is: there is any way to (for v3)
snmp[_async]_send() return immediately so i can send other GET PDU ?

regards,

Mateus