This was easier than I though...

but took longer than it should have for me to figure it out.
You can now pick up mice. Added basically the same things diona use for this feature.

code/modules/mob/holder.dm

@@ -62,6 +62,7 @@
 	var/obj/item/weapon/holder/H = new holder_type(loc)
 	src.forceMove(H)
 	H.name = name
+	H.icon_state = icon_state
 	if(desc)	H.desc = desc
 	H.attack_hand(grabber)
 
@@ -73,14 +74,12 @@
 //Mob specific holders.
 
 /obj/item/weapon/holder/diona
-
 	name = "diona nymph"
 	desc = "It's a tiny plant critter."
 	icon_state = "nymph"
 	origin_tech = "magnets=3;biotech=5"
 
 /obj/item/weapon/holder/drone
-
 	name = "maintenance drone"
 	desc = "It's a small maintenance robot."
 	icon_state = "drone"
@@ -90,3 +89,8 @@
 	name = "pAI"
 	desc = "It's a little robot."
 	icon_state = "pai"
+
+/obj/item/weapon/holder/mouse
+	name = "mouse"
+	desc = "It's a small, disease-ridden rodent."
+	icon_state = "mouse_gray"

code/modules/mob/living/simple_animal/friendly/mouse.dm

@@ -30,6 +30,7 @@
 	maxbodytemp = 323	//Above 50 Degrees Celcius
 	universal_speak = 0
 	can_hide = 1
+	holder_type = /obj/item/weapon/holder/mouse
 
 /mob/living/simple_animal/mouse/handle_automated_speech()
 	..()
@@ -63,7 +64,6 @@
 	icon_dead = "mouse_[mouse_color]_dead"
 	desc = "It's a small [mouse_color] rodent, often seen hiding in maintenance areas and making a nuisance of itself."
 
-
 /mob/living/simple_animal/mouse/proc/splat()
 	src.health = 0
 	src.stat = DEAD
@@ -73,6 +73,11 @@
 	if(client)
 		client.time_died_as_mouse = world.time
 
+/mob/living/simple_animal/mouse/attack_hand(mob/living/carbon/human/M as mob)
+	if(M.a_intent == I_HELP)
+		get_scooped(M)
+	..()
+
 //make mice fit under tables etc? this was hacky, and not working
 /*
 /mob/living/simple_animal/mouse/Move(var/dir)