Custom Ragdol limb assistance/guidance

i do so hope this is in the right area, if not, then please ignore me.

i recently tried to take the arms from Adam jensen from Deus Ex human machinama and put them on the scout from TeanFortress 2. needless to say, it didn’t work out as i couldn’t figure out how to do so, and the tutorials i looked up only made me disheartened when i tried and failed to follow them (most did not involve TF2 models anyway, but i tried none the less)

any assistance would be greatly appreciated, and falling all else, is there anyone i could pay to do it for me? (i prefer to learn how to do it myself though so as not to waste anyone time).

again, ANY assistance is appreciated and thank you for your time.