I've actually seen this:

Assuming the "myfield" field is C(5)

index on myfield tag myfield1
index on substr(myfield,2) tag myfield2
index on substr(myfield,3) tag myfield3
index on substr(myfield,4) tag myfield4
index on substr(myfield,5) tag myfield5

select * from mytable where:
myfield=SearchMe or;
substr(myfield,2)=SearchMe or;
substr(myfield,3)=SearchMe or;
substr(myfield,4)=SearchMe or;
substr(myfield,5)=SearchMe

With descent results. It's clunky and inserts into the table will be slower because of all of the index updating, but... It works.