Simply put, you fake it. There is no real correlation between MR and Attributes.
If one is being totally fixated, tho', one can fake 4 from MR, and a 5th can be moderately fudged...:
For creatures with MR ≤ 100 in T&T 5
Cn = MR
St = 12+MR/6, round down
Dx = 12+MR/6, round up
Lk = 12+MR/6, round down
Ch = -(1+(MR/10))d6
IQ = 3d6
Pow = 3d6
For creatures with MR ≤ 100 in T&T 7.x
Cn = MR
St = 12+MR/8, round up
Dx = 12+MR/8, round up
Lk = 12+MR/8, round down
Sp = 12+MR/8, round down
Ch = -(1+(MR/10))d6
IQ = 3d6
Wz = MR/10
Trade luck for dex and strength to be able to wield the correct dice of weaponry. Over 5D you'll usually need to go 2 handed. Over 10D, you'll need to use magic weapons.
Explanation of why...
Since MR/2 is adds, and (ST-12)+(DX-12)+(LK-12)= Adds, dividing MR by 6, and adding 12, gets you roughly equal stats for the three that determine adds.
In T&T 5.x, POW is ALWAYS x1 if it's used. Same with SPD in 5.0. Since they don't contribute to MR, they can be generated independently.
Negative Charisma being equal to dice rolled is a shortcut I've always used; it gives a good range, and means big beasts can be REALLY scary.
In 7.X, SPD also is an adds contributing stat... so, divide MR by 2 to get adds, then by 4 adds stats...
IQ is only vital to spellcasters; most monsters don't need lots.
Pow in 5.X is optional; in 7, Wiz is standard, and MR is listed as Wiz=MR/10 on p131 of 7.5.
Also, damage dice for PC-style characters are by weapon... with unarmed being 1d. the biggest 1h weapons run 5D+1 (warhammer St 16 Dx 3) at 99MR, I'm needing 10D, so a pair of pilae produces 10D+0, and requires St12 ea and Dex 8 each, for St 24 and Dex 16... 100/8=12.5, plus the 12 base...
Example MR 99 Conversion
Base is 10D+49 for MR99
St 25
Dx 25
Sp 25
Lk 24
IQ random
Ch 10d6 - should be about -35
Con 99
Wz 10
Attack: 10D+49 (2x pilum)