I'm going through the same thing as you right now. My female is a little over 2 months old and I'm weaning her onto mealies.
Last night I tried for the first time and all I did was throw a mealie into the middle of her tank right infront of the hide she was in. It wiggled around enough to get her attention (also it was dinner time), so she slowly crept out to investigate it and found it quite tasty. Polished off 4 more 3/4" mealies. I put a small plastic container in incase she wanted to eat overnight, but she hadn't touched them this morning. She saw them in it and crept up to it to investigate last night just before I went to bed, but for some reason she didn't attack them in the dish and went back to her hide. She might have just not been hungry anymore, or maybe she wasn't sure about eating out of a dish. (she's always had to hunt crickets out in the open)
I'm hoping tonight she'll eat right out of the dish, so I'm going to let her try that first. If she isn't cool with that yet, I'll throw them in one at a time for her to hunt until she gets the idea and ease her into the dish.
It seems like the key is movement. She wants to hunt something and it has to grab her attention and wriggle. If the mealie isn't moving much, try putting it on the hot side of the tank because it should be more active that way. Or pick out one that seems very active. Maybe try them one at a time so your leo isn't overwhelmed by a group of them wriggling.
Just thought I'd share my experience since we seem to be in the same spot. Hope this helped.
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Blaine
0.0.1 HY/Patternless/Normal Leo (Echo)