Extending BLToolkit expression builder

[postjazz]

Hi!

I am using BLToolkit in a 3-tier application together with Zyan and
InterLinq.
LINQ queries are constructed at the client-side, sent to server and
executed with BLToolkit.

BLToolkit assembly resides on the server-side only (for security
reasons).
I'd like to use my own methods in LINQ queries and hook into BLToolkit
expression builder to convert them to some custom SQL.
I can't use SqlExpression and SqlFunction attributes because they are
defined in BLToolkit assembly which is not available on client.

Is it possible to define my own attribute similar to SqlExpression
which will be processed by BLToolkit in a similar way?
Or, alternatively, can you provide some extension point to
ExpressionBuilder so I can catch expressions which are not handled by
BLToolkit to process them myself?

Thanks.