From Vaclav in an earlier thread:

Hi,
I don't know about the patch, but for storing something with registered
contact you can use "reg_avps" (AVPs stored with contact; you need only
to set a flag to them before you call save and if you want to get them
back, you can call "read_reg_avps"). So if you are able to translate
Path into AVP(s) you can use it... It is not tested and not described
but it can work...  :-) 

Something like this was working some time ago:

avpflags regavps;

modparam("usrloc", "reg_avp_table", "contact_attrs");
modparam("usrloc", "reg_avp_flag", "regavps")

route {
	...

	if (method=="REGISTER") {
		$t.a = @msg["P-Avp"];
		$t.neco = "pokus";
		setavpflag("$t.a","regavps");
		setavpflag("$t.neco","regavps");

		save("location");
		break;
	}
	...
}

branch_route[1]
{
	read_reg_avps("location", "$t.uid");
	xlog("L_ERR", "$t.a = %$t.a");
	...
}

If somebody will be interested, I can try to describe it better (and
test a bit with Ottendorf)...

	Vaclav