Odd Slur

[Will Oram]

Hi,

If I want to cross staves, I call this on the bass line (with nothing  
more than skips on treble):

% measure 1
\times 2/3 { r8 c'-[-( f-] } \times 2/3 { aflat-[ f aflat-] } \times  
2/3 { c-[ aflat c-] } \times 2/3 { f-[ c f-] }

% measure 2
\translator Staff = "up"
\times 2/3 { aflat-[ f aflat-] } \times 2/3 { c-[ aflat c-] }
\clef "treble"
\times 2/3 { f-[ c f-] } \times 2/3 { aflat-[ f aflat-] }

% measure 3
\times 2/3 { c-[ aflat c-] } \times 2/3 { f-[ c f-] } \times 2/3 {  
aflat-[ f aflat-] } c-.-)-[ g-\mp-]-(
        
% measure 4
aflat-[ e f csharp-] d-)-[ aflat'-(-\> f d-]-)-\!

In other words, start on the bass line, and cross into treble in the  
second measure. The slur created with it, looks bizarre and needs some  
tweaking. The docs at  
http://www.lilypond.org/doc/v1.8/Documentation/user/out-www/lilypond- 
internals/Slur.html are OK, except I don't know what I want. I assume I  
want to tweak control-points? Where are these points and what should I  
do with them?

Thanks.