ok this may not help at all, but I had pretty good success with a high reflexed bow doing this,,
I could not get it to go on the tiller tree to see the bend,,but wanted to exercise the limbs before bracing,,
I got a bucket full of rocks( ok I know this sounds primitive) that weighed my target weight 50#,,
then I put the bow on long string and lifted the bucket,, that way I knew I was not going over target weight,,
finally I put the bow in the vise and hooked the bucket to the long string and let it sweat a bit,,
when I got the limbs moving enough I got it braced,, the 50# weight was pulling the reflex to about even,, when I got it strunt the first time, I nearly missed the weight as the sinew gave in quite a bit,, so as mentiioned string when it feels a bit heavy,,