I’ve been offering this for a while, with a few advantages.
http://forum.mikrotik.com/t/blacklist-filter-update-script/89817/1
I use Dynamic address lists. This keeps the IP’s in memory and dramatically reduces the number of flash writes. The script tells the server the some basics about the router, and the server is able to send more or less addresses, based on the CPU and memory. This is helpful because in addition to the DShield and Spamhaus blocklists, My server collects IPs from just over 100 other Mikrotik routers and IDS boxes looking for active attacks. So, there are days that the list can ballon up to over 50k IPs during an active DDOS attack.