Very easily. Locate the file /omd/sites/checkmk/local/share/check_mk/checks/agent_mikrotik (attn.: not the special agent) and insert two lines.
Before:
args += " -p " + quote_shell_string(params["password"])
args += " -c " + str(params["connect"])
After:
args += " -p " + quote_shell_string(params["password"])
if params["nossl"]:
args += " -n"
args += " -c " + str(params["connect"])
This should do the trick. If that works for you, I’ll update the package in checkmk exchange.
ttr