Question about snmpset and scripts on routeros

Hello all,
I am working hard to get a setup with Microtiks CCRs up and running. In this matter I created a few scripts to keep a firewall address-list updated. I can run these scripts from snmpset which is really cool, but I cant really solve how to catch the IP address I get from snmpset. Can someone give me a hint?

SNMP client
snmpset -c public -v 2c <routeros_ip> 1.3.6.1.4.1.14988.1.1.8.1.1.3.2 a 10.100.1.1

Routeros (script 2)
/system script add name=add_to_block policy=read,write,policy,sensitive source=“/ip firewall address-list add list=block_list address=$_uparam


I know the $_uparam must be wrong, but can someone give me an idea on how to do it right, eventually hand me an example.

/Casper