See the second verse of this song for another version of the "when I die" line and see the fourth verse of the same rhyme for a "pickle my bones with alcohol" line:

WHEN MY WIFE DIES
W'en my wife dies, gwineter git me anudder one;
A big fat yaller one, jes lak de yudder one.
I'll hate mighty bad, w'en she's been gone
Hasn't no better 'oman never nowhars been bo'n.

W'en I comes to die, you mus'n bury me deep.
But pit Sogrum mollasses close to my feet.
Put a pone a' co'n bread way down in my han'
Gwineter sop on de way to de Promus Lan'.

W'en I goes to die, Nobody mus'n cry,
Msu'n dress up in black, fer I mought come back.
But w'en I'se beed dead. an' almos' forgotten;:
You mought think about me an' keep on a-trottin'.

Really, we'en I'se been dead, you needin' bury me at tall.
You mought pickle my bones down in alkihall;
Den fold my han's "so", right across my breas':
An' go an' tell de folks I'se done gone to "res".

Source: Thomas W. Talley: "Negro Folk Rhymes" {Kennikat Press Edition, 1968, p. 26; originally published by The Macmillan Company, 1922}

The song makes reference to some 18th century [and earlier] African American burial customs that have their origins in Africa. I'm particularly referring to the 2nd verse, and also the fourth verse's reference to folding the deceased person's hands "just so". I'm wondering if the "pickling the bones in alcohol" was a way of preparing the body prior to burial.

Of course, the first verse's lyrics "A big fat yaller one, jes lak de yudder one" is a referent to some African American skin color preferences for "yallar" [light skinned Black] women.